Roundup: 9 Radeon HD 6850s! - BeHardware
>> Graphics cards

Written by Damien Triolet

Published on February 23, 2011

URL: http://www.behardware.com/art/lire/821/


Page 1

Introduction



Following the GeForce GTX 460 1 GBs, weíve decided to take a look at the Radeon HD 6850s customized by AMDís partners. They give a comparable level of performance to the GeForce GTX 460s and give good gaming for a decent price. They are however considered to have lower overclocking potential, something weíre going to check.



Barts
The Radeon HD 6850s are based on Barts, a GPU which is a sort of low-cost version of Cypress, used in the Radeon HD 5800s. A few small improvements have however been made, especially in terms of tessellation performance and support for DisplayPort 1.2 and MVC hardware decoding, the format used for 3D Blu-rays.

Barts is made up of 224 vec5 processing units (1120 Ďcoresí) divided into 14 blocks, two of which are disabled in the version used for the Radeon HD 6850, bringing the number of vec5 processing units down to 192 (960 Ďcoresí). The processing units are supplied by a 256-bit GDDR5 memory controlller, which has been simplified to reduce costs and which hasnít been designed to clock very high.


You can find more details on this in the Radeon HD 6870 and 6850 test and more recent performance measurements in the GeForce GTX 560 Ti test.


Page 2
Specifications, GDDR5

Specifications

The Radeon HD 6850 is situated mid-way between the Radeon HD 5770 (renamed as the Radeon HD 6770) and the Radeon HD 6870. Itís closer to the first in terms of processing power but closer to the second in terms of memory bandwidth.


GDDR5 Hynix 1.25 GHz for everyone

All the Radeon HD 6850s that we tested were equipped with Hynix GDDR5 certified at 1.25 GHz although itís only clocked at 1 GHz on models that use the reference clocks and 1.1 GHz on overclocked models. We imagine that this is because AMD has simplified the Barts GPU memory controller, stopping it from taking advantage of higher clocks. We will however check to see if thereís a margin for overclocking.

Remember that these clocks represent those at which commands are sent to the memory, but that in the case of GDDR5 data transits at twice the frequency, something we include in our spec tables so as to allow direct comparison with GDDR3.


Page 3
Test protocol

Test protocol
For this test, we used the protocol we introduced in our report on graphics cards and thermal characteristics, which allows us to make a detailed analysis of the various choices AMDís partners have made here.


We measured the temperature of the GPU and various components under actual usage conditions, in an Antec Sonata 3 box and we also took an infrared shot, opening the box for as short a time as possible. We also measured noise levels under actual usage conditions, namely with the cards in a closed casing. We placed the sonometer 60cm from the casing.

We altered the protocol slightly by adding an additional phase because we carried out the temperature test for each card at maximum overclocking. This enabled us to observe the power stage when put under increased stress, but also allowed us to verify overclocking stability further.


When several overclocked variants of the same model are available, we tested just one of them. Thereís no need for a detailed analysis of the performance of the different solutions because all the cards would give identical performances at identical clocks. This is therefore dealt with briefly in the report.

We concentrated on the most common models and, for now, weíre able to present results on eight of them, in addition to the reference card. We will of course add models in the future if need be.


Page 4
Radeon HD 6850 reference card

Radeon HD 6850 reference card
Both the cooling system and the PCB on the reference model were developed by AMD and were used at launch of the Radeon HD 6850. This model is not however, to our knowledge, available in stores. Although some online resellers display it as their Ďgenericí model, there is no guarantee that it will be the card delivered. We arenít able to suggest any products on the market that correspond to it and it is therefore only given here for information purposes.


The card




At 23cm, the reference card is longer than the GeForce GTX 460 reference card, which is 21 cm long. Connectivity is thorough with two DVI Dual Link outs, an HDMI 1.4a out and two mini-DisplayPort 1.2 outs.

Its PCB has a 6-pin PCI Express connector and a power stage with four GPU phases. The Hynix GDDR5 memory is certified at 1.25 GHz although only clocked at 1 GHz (2 GHz for data).

The reference cooler is based on a blower design and expels the hot air from the casing. Thereís a small but sturdy radiator with an aluminium heat dissipation block fixed to a copper vapour chamber. The sensitive power stage components are in contact with the cooler structure.


Infrared thermography

Graphics card at idle.


Graphics card in load.


Overclocked graphics card in load.


System at idle.


System in load.

Although a little hotter at idle than other recent Radeons, the Radeon HD 6850 is pretty well cooled and this includes when itís in load and overclocked. Its power stage handles the load no problem.


Temperature and noise readings

The readings confirm that the card expels most of the hot air from the casing. This is done quietly, whether at idle or in load.


Our opinion
With four phases for the GPU power supply and a vapour chamber to dissipate the heat given off, the reference design for the Radeon HD 6850 is very efficient and itís regrettable that it isnít available in stores. We imagine that AMDís partners, and even AMD itself, preferred to push various other, less expensive designs onto the market rather than this model, which in the end has served mainly as a press test model.


Page 5
Asus HD 6850 DirectCU

Asus EAH6850 DirectCU
Thereís just one Asus Radeon HD 6850 model: a DirectCU model. It offers minimal overclocking, with the GPU clock up from 775 to 790 MHz (+2%) while the memory is clocked at the reference clock. Itís on sale at Ä170.


The card



24cm long, the Asus Radeon HD 6950 is slightly longer than the reference model. Its PCB has been designed for two 6-pin PCI Express connectors, which makes us think that in fact the same PCB is used here as for the Asus Radeon HD 6850 and 6870. Given that these connectors are placed on the top and not at the back of the card, this PCB doesnít actually require any more space in the casing.

While the PCB has been designed for a 4 phase GPU power supply, only three are used on this model. Note that they have been placed between the connectors and the GPU and not at the back of the card as they are on the reference design.

Asus has retained the connectivity used on the Radeon HD 5000s rather than going for the connectivity used on the reference Radeon HD 6000s: 2 DVI Dual-Link outs, an HDMI out and a DisplayPort out. The Hynix GDDR5 is certified at 1.25 GHz.

A metal bar guarantees the cardís rigidity to prevent any problems there may be when handling it, especially as the cooler is only fixed around the GPU with four screws. The cooler is made up of an aluminium radiator with two copper plated heatpipes which are in direct contact with the GPU. An 8cm fan is mounted on top. Thereís a small radiator for the sensitive power stage components.


The bundle

A CD with drivers and a manual, a quick installation guide, a DVI to VGA adaptor, a small CrossFire connector, a double molex to 6-pin PCI Express power supply cable convertor and a disk holder came with the Asus card.

The card is guaranteed for three years.

Asus also supplies the SmartDoctor overclocking/tweaking software. This allows you to control the fan and protection mechanisms while modifying the GPU voltage, in addition of course to any overclocking.




Infrared thermography

Graphics card at idle.


Graphics card in load.


Overclocked graphics card in load.


System at idle.


System in load.

The EAH6850 DirectCU is well cooled.


Temperature and noise readings

The Asus Radeon HD 6850 is pretty quiet, at idle and in load and handles very similarly to the reference card. However no hot air is expelled from the casing, as you can see from the fact that the temperature of the air coming out of the casing is identical at idle and in load.


Our opinion
With the EAH6850 DirectCU, Asus is offering an excellent Radeon HD 6850, well cooled, quiet and well finished. It will therefore be a viable replacement for the reference model which canít be found in stores.


Page 6
Gigabyte HD 6850

Gigabyte HD 6850
The Gigabyte Radeon HD 6850 is available in two versions:

Gigabyte Radeon HD 6850: Ä170
Gigabyte Radeon HD 6850 OC: Ä180

We tested the standard version. While the OC version uses the same cooler, it has a different PCB, with a completely revised power stage.


The card



It looks to us as if Gigabyte has used a second reference PCB supplied by AMD to its partners, probably to reduce costs in comparison to that used on press samples. This PCB is more compact, with the card measuring 21.5 cm and the power stage placed between the connectors and the GPU. This power stage was designed for four phases but only three are used here. The connectivity is similar to that used for the Radeon HD 5000s: 2 DVI Dual-Link outs, an HDMI out and a DisplayPort out. The Hynix GDDR5 is certified at 1.25 GHz.

The cooler casing extends 2 cm out the back of the card, mainly an aesthetic choice because the radiator itself only extends 0.5cm out the back. This radiator is entirely in aluminium with two heatpipes extending from it. A small additional radiator is also included for the sensitive power stage components. Two 8cm fans take care of cooling.


The bundle

Gigabyte delivers its card with a CD containing the drivers (not in the press sample), a manual, a DVI to VGA adaptor, a small CrossFire connector and a double molex to 6-pin PCI Express power supply cable convertor.

Gigabyte guarantees its card for two years.


Infrared thermography

Graphics card at idle.


Graphics card in load.


Overclocked graphics card in load.


System at idle.


System in load.

The Gigabyte card is very well cooled.


Temperature and noise readings

Although the readings confirm that the card is well-cooled, it is rather noisy. While levels arenít too bad in load, at idle it isnít completely quiet, as most of the other models are. It only expels part of the air from the casing.


Our opinion
While we were particularly impressed with the Gigabyte GeForce GTX 460, our opinion of this Radeon HD 6850 is rather mitigated. Its cooling system, similar to the one used on the GTX 460, doesnít appear to have been very well calibrated, or really adapted to the size of the PCB.


Page 7
HIS HD 6850

HIS HD 6850
HIS is also marketing a Radeon HD 6850 at the clocks used for the reference card and on sale at Ä170.


The card



Like many Radeon HD 6850s, the basic HIS model looks as if itís using the AMD reference PCB designed for use on partner cards. The same connectivity is used as on the Radeon HD 5000s and it has a 4-phase power stage, only 3 of which are used here. The Hynix GDDR5 is certified at 1.25 GHz. The card is relatively compact (21.5 cm long), however the 6-pin PCI Express connector is situated at the back of the card.

HIS has opted for a small circular cooler, the radiator with two heatpipes joined to a copper base. Thereís a small 7cm fan for cooling and a small radiator is fixed to the sensitive power stage components.

When you have the card in hand, the plastic casing seems to lack rigidity and gives a rather cheap feel to the card overall.


The bundle

HIS delivers its card with a CD containing the drivers, a small guide on how to mount it, a HIS sticker, a DVI to VGA adaptor, a CrossFire connector and a double molex to 6-pin PCI Express power supply cable convertor.

HIS guarantees its card for two years.


Infrared thermography

Graphics card at idle.


Graphics card in load.


Overclocked graphics card in load.


System at idle.


System in load.

The card is pretty well cooled although the GPU does heat up a bit more than on other models.


Temperature and noise readings

The temperature readings confirm that it gets a bit hotter and also show that a good proportion of the hot air is extracted from the casing. Although the card is quiet at idle however, itís a good deal noisier in load.


Our opinion
The basic HIS Radeon HD 6850 is definitely not the model we advise. Itís rather cheap looking and the cooler isnít very effective, making more noise than other models while not keeping the GPU temperature as low.


Page 8
HIS HD 6850 IceQ 4+ Turbo

HIS HD 6850 IceQ X Turbo
As well as its first model, HIS has also brought out an IceQ X version. Itís available in two variants:

HIS Radeon HD 6850 IceQ X: Ä170
HIS Radeon HD 6850 IceQ X Turbo: Ä180

The Turbo GPU is overclocked to 820 MHz and the memory to 1100 MHz, against 775 and 1000 MHz for the standard model, which is on the standard clocks. We tested the Turbo model.


The card



HIS uses the same PCB here as on its first Radeon HD 6850 and with an identical configuration. One of the 4 phases on the GPU power stage isnít used. The memory is also identical: Hynix and certified at 1.25 GHz.

The card is also the same size except for the four nickel chrome heatpipes which run from a copper base across its cooler. A small radiator is fixed to the sensitive power stage components while a 9cm fan takes care of the cooling. While the fan does the job, its quality is debatable and it makes a small mechanical noise. In a closed casing you wonít be able to hear it but you will if youíre running an open system.


The bundle

HIS delivers its card with a CD containing the drivers, a small guide on how to mount it, a HIS sticker, a DVI to VGA adaptor, a CrossFire connector and a double molex to 6-pin PCI Express power supply cable convertor.

The card is guaranteed for two years.


Infrared thermography

Graphics card at idle.


Graphics card in load.


Overclocked graphics card in load.


System at idle.


System in load.

This IceQ X HIS model is well cooled both at idle and in load, better than the basic model. The power stage does however heat up more given its higher clocks. This is particularly the case when the card is overclocked, especially as the card we received went quite high.


Temperature and noise readings

The readings confirm that the GPU is very well cooled, in all circumstances. Hot air isnít however expelled from the casing. The fact that it is well cooled isnít to the detriment of noise levels either: this model is quieter than the first HIS model, in spite of the factory overclocking.


Our opinion
The Radeon HD 6850 IceQ X is definitely a better buy than the basic HIS model. It has a more effective cooler and a more flattering design and is one of the better Radeon HD 6850s weíve tested. The only small reservations we have is that the fan makes a slight mechanical noise that can be heard in an open system and that the higher overclocking potential would have benefitted from a full 4-phase power stage.


Page 9
PowerColor HD 6850 PCS+

PowerColor HD 6850 PCS+
The Radeon HD 6850 PCS+ is one of three Radeon HD 6850 models marketed by PowerColor. The GPU has been overclocked to 820 MHz and the memory to 1100 MHz, against 775/1000 MHz for the reference card. Itís on sale at Ä170 or at Ä190 in a bundle with Call of Duty Modern Warfare 2. This bundle is what was supplied to us PowerColor.


The card



For the Radeon HD 6850 PCS+, PowerColor seems to have used the reference PCB that AMD has designed for cards that go onto the market (as opposed to the PCB on the reference model sent to the press) In contrast to other manufacturers who use this PCB however, PowerColor is using all four phases for the GPU.

The cooler is made up of aluminium base and radiator with three heatpipes and is cooled by a 9cm fan. No radiator has been fixed to the power stage, with PowerColor probably judging that the stress here is reduced by the use of four instead of three phases. Note that the casing sticks out a bit at the back of the PCB, extending the card length to 22cm. In practice, this doesnít make any difference as the power supply connector at the back of the card requires more space that this.


The bundle

PowerColor delivers its card with a manual and CD for the drivers, a quick installation guide, Call of Duty Modern Warfare 2 (optional), a DVI to VGA adaptor and a small CrossFire connector.

The card is guaranteed for 2 years.


Infrared thermography

The graphics card at idle.


Graphics card in load.


Overclocked graphics card in load.


System at idle.


System in load.

The card is well-cooled overall though the GPU temperature seems higher than average. Note however that a good deal of hot air is directed towards the hard drive bay.


Temperature and noise readings

The full readings confirm what we see on the infrared thermography and show that the card expels a small proportion of hot air out of the casing. Although effective in terms of keeping temperatures down, this cooler is far from being quiet in load and is the noisiest of those tested for this report. This is due to the fact that the fan is then required to run at full speed.


Our opinion
PowerColor has signed a disappointing Radeon HD 6850 PCS+ here, especially when it comes to the cooler, which is not up to par in terms of what is nevertheless a relatively undemanding GPU and makes too much noise in load.


Page 10
Sapphire HD 6850

Sapphire HD 6850
The first Sapphire Radeon HD 6850 follows the reference card clocks. Itís on sale at a very attractive Ä150.


The card



Sapphire is using the reference PCB, which gives us a relatively compact model here, at just 21.5cm long. Although there are four phases available for the GPU power stage, only three are used. A small radiator is positioned here to cool the sensitive power stage components.

The cooler is made up of an aluminium radiator with two large heatpipes connected to a base with a copper insert. Thereís an 8cm fan for cooling.


The bundle

Sapphire delivers its card with a CD for drivers, an installation guide, a Sapphire Select Club access card, a DVI to VGA adaptor, a small CrossFire connector and a molex to 6-pin PCI Express power supply cable convertor.

Sapphire guarantees this model for two years.


Infrared thermography

Graphics card at idle.


Graphics card in load.


Overclocked graphics card in load.


System at idle.


System in load.

This Sapphire card is well-cooled overall. It does however send quite a bit of hot air straight towards the hard drives.


Noise and temperature readings

The GPU remains well-cooled and a small amount of air is expelled from the casing. Although the card is very quiet in idle, it does make iself heard in load.


Our opinion
Sapphire has produced a card with the sole problem being noisier in load than the best models. It is however on sale at a very low price which will certainly make plenty of users ready to ignore this small fault, especially as the GPU temperature remains relatively stable. It will therefore be possible to reduce the fan speed slightly.


Page 11
Sapphire HD 6850 TOXIC

Sapphire HD 6850 TOXIC
The second Sapphire Radeon HD 6850 is part of its TOXIC range. It is overclocked at 820/1100 MHz instead of 775/1000 MHz, increases of 6% and 10% for the GPU and memory repectively. Itís on sale at Ä170.


The card



Sapphire has gone for the Radeon HD 6870 reference PCB for the Radeon HD 6850 TOXIC. Itís longer, 24cm, and two 6-pin power connectors are required. There are four power phases and theyíre all used.

The cooler used is a low cost verion of the Radeon HD 6870 reference cooler. Its architecture is identical: aluminium radiator with 3 heatpipes and fan. Sapphire have however reworked the frame design and replaced the copper base with an aluminium one with a copper insert. Thereís a plate covering the PCB and itís in contact with the memory modules as well as the sensitive power stage components.


The bundle

Sapphire delivers its card with a CD for drivers, an installation guide, a Sapphire Select Club access card, a DVI to VGA adaptor, a small CrossFire connector and a molex to 6-pin PCI Express power supply cable convertor.

Sapphire guarantees this model for two years.


Infrared thermography

Graphics card at idle.


Graphics card in load.


Overclocked graphics card in load.


System at idle.


System in load.

Both the GPU and power stage on the Radeon HD 6850 TOXIC are very well cooled.


Temperature and noise readings

These readings confirm that the card is well cooled and that a good part of the air is extracted from the casing. Although the noise in load is lower than the basic Sapphire card, the TOXIC is still louder than other models.


Our opinion
With the Radeon HD 6850 TOXIC, Sapphire is marketing a factory overclocked model at the price most other manufacturers are charging for their basic models. It has a big power stage which will prevent overheating during extreme overclocking, but it does get a little noisy in load.


Page 12
XFX HD 6850 (ZDFC)

XFX HD 6850 (ZDFC)
XFX is marketing two different models under the same name but a different reference. HD-685X-ZNFC/ZNBC for the first and HD-685X-ZDFC for the second. They use totally different coolers. A single fan with a design that looks very similar to the basic HIS model for the ZNFC/ZNBC and two fans for the ZDFC, which is the one we tested. Itís on sale for Ä190, in general with the Dual Fan label to distinguish it.


The card



XFX has gone for the design used on the reference cards on sale and only use three of the four available GPU phases. The cooler sticks out 1cm from the back of the card, making it 22.5cm long but this doesnít affect the amount of space required in practice given that this is similar to the amount of space required by the 6-pin power connector at the back.

The cooler is made up of an aluminium radiator with two copper heatpipes in direct contact with the GPU. Two 8cm fans take care of cooling and thereís a small radiator for the sensitive power stage components.


The bundle

XFX delivers its card with a CD for drivers, an installation guide for drivers, a guide to mount the card, an advertising leaflet for power supplies and a little ĎDo not disturbí sign to stick on the door when youíre gaming. No adaptors are supplied.

The card is guaranteed for two years.


Infrared thermography

Graphics card at idle.


Graphics card in load.


Overclocked graphics card in load.


System at idle.


System in load.

The XFX Radeon HD 6850 ZDFC is the best cooled model of those we have tested.


Temperature and noise readings

The readings confirm the infrared thermography and only a very small part of the hot air is extracted from the casing. Unfortunately the excellent temperature readings are achieved to the detriment of noise levels.


Our opinion
XFX obviously chose to prioritise temperatures when it was calibrating its cooler. While you can correct this manually to reduce noise levels in load, this wonít reduce the prohibitive price of this non-overclocked model that is delivered without any adaptors at all!


Page 13
Summary of results

Summary of results
Here weíve brought together all the temperature readings taken during the tests. Weíve highlighted the results that stand out:



At idle all the solutions tested behave in a similar way.




In load, we noted a few differences. While the reference card expels most of the hot air out of the casing, only the standard HIS and Sapphire TOXIC cards also do this. Most of the other cards only expel a small amount of air, or even none at all (the Asus DirectCU and HIS IceQ X).


Page 14
Overclocking and performances

Overclocking
Obviously each individual sample of any model can react differently when overclocked but we tried to push all the cards in our possession so as to be able to observe any generalities. With an open test system, we used Furmark to load the cards to a maximum, increasing the clock by increments of 25 MHz each time to make sure the cards were stable at each increase. Next we looped Crysis Warhead 4x to measure performance and then validated temperature readings with a closed casing. We rechecked the overclocking if a problem was detected at any of these stages, something that was the case for several cards as Furmark is not always the best adapted tool to validate overclocking.

Note that GDDR5 memory has various error detection mechanisms which mean that in the case of significant overclocking, the memory is stable but slows down to repair errors linked to overclocking, either by returning corrupted data or recalibrating clocks. We therefore generally avoid overclocking it.

We did however quickly note that once the Radeon HD 6850 is overclocked, its performance is limited to a great extent if the memory isnít clocked up as well. We therefore spent some time on this, especially as the Hynix GDDR5 used on all the cards tested is certified at a 25% higher clock than that used by default.

Here are the clocks that we were able to obtain:


We noted therefore that we could overclock the GDDR5 memory up to 1150 Mhz on a Radeon HD 6850. Beyond that, with just one exception, we noted a small dip in performance linked to very noticeable jumpiness. It is possible that in the case of the card where this did not occur, the HIS Radeon HD 6850 IceQ X Turbo, it was because the GPU also runs at a higher clock. The limitation may therefore come from the difference between the GPU clock and the memory clock, something that isnít impossible as the memory controller has been simplified.

Itís difficult to say if the higher clocks on the IceQ X Turbo result from handpicking of GPUs by HIS or if itís simply down to the fact that the particular card we tested supported higher overclocking. All the other Radeon HD 6850s managed to go up to 900 or 925 MHz, with no advantage going to the factory overclocked models.

While minimum GPU overclocking observed on the GeForce GTX 460 1 GB was 22%, here itís 16%. The GeForce GTX 460s therefore have an advantage but not as big a one as all that, with the Radeon HD 6850s also having a decent overclocking margin. Moreover, on the Radeon HD 6850s it can be fully exploited without resulting in any power stage issues, , which can be a problem with the GeForce GTX 460 1 GBs.

Note also that the GPU voltage is not fixed and can vary from one model to another. This gives AMD more flexibility to validate its GPUs at a given spec.


Performances
For information, we observed the performance of all the cards at their original clocks and overclocked in Crysis Warhead at 1920x1200 with 4x antialiasing and in Gamer mode.


In comparison to the reference clocks, we gained between 14% and 19% with maximum overclocking. This was similar to the gain observed on the GeForce GTX 460s, with the HD 6850s benefitting from GDDR5 overclocking to improve yields.


Page 15
Temperature and noise levels

GPU temperatures
We have shown the various GPU temperatures at idle and in load, as well as in load when the card had been overclocked.



Noise levels

Whether at idle or in load, the reference model is relatively quiet and itís difficult to do better, especially as one of the goals with the alternative coolers is to reduce costs.

Only the Asus card, and the standard IceQ X (something we are assuming in view of the relatively good results of the factory overclocked IceQ X Turbo that we tested), do as well as the reference model, with the other cards being a little noisier in load, the noisiest being the Power Color PCS+.


Page 16
Energy consumption

Energy consumption
We measured the energy consumption of the different cards, keeping in mind that thereís often a variation between identical cards of the same model, due, among other things, to current leakage and GPU voltages. Moreover, some run at higher clocks as they are factory overclocked.

We measured energy consumption directly on the graphics cards themselves.


At idle, we measured energy consumption as varying between 19W and 24W, a difference that may be linked to current leakage and the energy consumption of the fan.

In load the differences are bigger and the reference model consumes a good deal less than all the other Radeon HD 6850s tested. We suppose that this results from a better yield from the power stage and/or the GPU voltage which was also the lowest of all the cards tested. The Radeon HD 6850s that are marketed by AMDís partners and are not factory overclocked, consume between 7 and 21% more! The factory overclocked models draw from 20 to 34% more, with the PowerColor drawing most, which may also result from the fact that the fan runs at full speed and the fact that the GPU voltage is somewhat higher.


Page 17
TI: graphics cards at idle

Infrared thermography: graphics cards at idle

Reference Radeon HD 6850


Asus EAH6850 DirectCU


Gigabyte HD 6850


HIS HD 6850


HIS HD 6850 IceQ X Turbo


PowerColor HD 6850 PCS+


Sapphire HD 6850


Sapphire HD 6850 TOXIC


XFX HD 6850 (ZDFC)

All the Radeon HD 6850s are well cooled at idle and do slightly better than the reference model.


Page 18
TI: graphics cards in load

Infrared thermography: graphics card in load

Reference Radeon HD 6850


Asus EAH6850 DirectCU


Gigabyte HD 6850


HIS HD 6850


HIS HD 6850 IceQ X Turbo


PowerColor HD 6850 PCS+


Sapphire HD 6850


Sapphire HD 6850 TOXIC


XFX HD 6850 (ZDFC)

In load, the power stage on these cards is what increases in temperature most, though these temperatures are still low enough not to pose any problem.


Page 19
TI: OC graphics cards in load

Infrared thermography: overclocked graphics cards in load

Reference Radeon HD 6850


Asus EAH6850 DirectCU


Gigabyte HD 6850


HIS HD 6850


HIS HD 6850 IceQ X Turbo


PowerColor HD 6850 PCS+


Sapphire HD 6850


Sapphire HD 6850 TOXIC


XFX HD 6850 (ZDFC)

Once the Radeon HD 6850s are overclocked, it is once again the power stage which heats up most. Some cards would have benefitted from a fourth phase for the GPU so as to reduce these temperatures during extreme overclocking. Note however that using a radiator on the sensitive power stage components does reduce temperatures, as the temperature readings for the PowerColor PCS+ (which uses four phases but no radiator) show.


Page 20
TI: systems at idle

Infrared thermography: systems at idle

Reference Radeon HD 6850


Asus EAH6850 DirectCU


Gigabyte HD 6850


HIS HD 6850


HIS HD 6850 IceQ X Turbo


PowerColor HD 6850 PCS+


Sapphire HD 6850


Sapphire HD 6850 TOXIC


XFX HD 6850 (ZDFC)

None of the Radeon HD 6850s pose any problem in idle.


Page 21
TI: systems in load

Infrared thermography: system in load

Reference Radeon HD 6850


Asus EAH6850 DirectCU


Gigabyte HD 6850


HIS HD 6850


HIS HD 6850 IceQ X Turbo


PowerColor HD 6850 PCS+


Sapphire HD 6850


Sapphire HD 6850 TOXIC


XFX HD 6850 (ZDFC)

In load, thereís no great difference overall, except when it comes to the hard drive bays, towards which a good part of the hot air is sent on the PowerColor PCS+ and standard Sapphire.


Page 22
Conclusion

Conclusion
After having reviewed several of the Radeon HD 6850s marketed by AMDís partners, it seems clear that thereís a gap between the excellent reference model and the rest. Indeed it seems as if AMD has developed two reference Radeon HD 6850s. The first model, not adapted to the price segment but with a sturdier power stage and a very efficient cooler, and the second, more economical model, with a PCB that is less costly to produce. The first was distributed to the press at launch of the Radeon HD 6850, while the second was used by partners for the solutions that were then put on the market.


This is not the first time that AMD has acted in this way and although we can see why they want to show their new products in the best possible light, it is regrettable that theyíve done so with a design as attractive as it is unrealistic for this price segment and which wonít in any case be available to customers.

We also noted some significant differences in the results obtained between the Radeon HD 6850s and the GeForce GTX 460s based on similar designs. While the Asus GeForce GTX 460 proved very noisy, the Radeon HD 6850 DirectCU, also from Asus, wasnít at all noisy. It has to be said that its fan cools a less demanding GPU and doesnít have to hit maximum revs.

Another example, the GeForce GTX 460 from Gigabyte stood out for its very good results but the same canít be said for the Gigabyte Radeon HD 6850, which however uses an almost identical cooler. This is down to the fact that, in our opinion, coolers need to be adapted to the specific solution theyíre used for. The Gigabyte model uses a big aluminium base, which is probably well adapted to a GPU such as the GF104 used on the GeForce GTX 460 which has a heatspreader to increase the contact area with the radiator base. However, this isnít especially the case with the small Barts GPU used in the Radeon HD 6850s, which doesnít have this type of heatspreader. Using copper makes the transfer of heat from the GPU to the radiator much more efficient here. A similar problem is probably also what makes the noise levels on the PowerColor Radeon HD 6850 PCS+ so high.


In the end the Asus Radeon HD 6850 DirectCU is the card thatís probably closest to the very good reference card (not on sale) and which is the model we advise you to look at first. With a very slight factory overclocking, designed simply to justify the use of an extra logo on the box, this Radeon HD 6850 is well cooled, quiet and the manufacturing quality is better than average.

Another model we also liked was the HIS Radeon HD 6850 IceQ X Turbo with a slight factory overclocking, good GPU cooling and relatively contained noise levels, although they would have been even lower with a better quality fan.

Finally, the two Sapphire cards are both worth a look for different reasons. The first, the basic card, is very competitively priced, though it does make slightly more noise in load - this can be reduced if you take the time to better calibrate fan speed. The second, the TOXIC model, has a sturdy GPU power stage, which will interest extreme OC enthusiasts who want to make the most out of a model that is very conducive to overclocking, without damaging the card in the long term.


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