NVIDIA GeForce 6600 GT AGP

NVIDIA GeForce 6600 GT AGP - BeHardware
>> Graphic cards

Written by Marc Prieur

Published on November 16, 2004

URL: http://www.behardware.com/art/lire/533/

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The GeForce6 6600GT

NVIDIA and ATI have become more and more interested in PCI Express for a few months now, because of end of the year sales and partnerships with OEMs. For the moment, however, the number of PCI Express is still limited. The lack of PCI Express Athlon 64 platforms and graphic cards has slowed down the development of this market. Aware of this issue and the difficult position of the GeForce FX in relation to the best selling Radeon 9800 Pro, NIVIDIA had to release a GeForce 6 6600 GT version compatible with the “good old” AGP slot!

The GeForce6 6600 GT
In a few words, the GeForce 6600 GT (already studied in this article) is to some extent half a GeForce 6800 GT. The number of pixel pipelines and vertex engines are reduced from 16 to 8 and 6 to 3, respectively. The bus memory was also changed to 128 bits.from 256 bits.

The GeForce 6 6600 GT includes all of the GeForce 6 architecture’s functions. Included are the Shader Model 3.0, which creates longer shaders and introduces dynamic branching, and full compatibility with FP16 format. So the 6600 GT is capable of HDR type lighting with more flexibility and efficiency. Finally, the 6600 GT integrates the PureVideo engine, which, in theory, is able to accelerate MPEG1/2/4 encoding. This function, however, isn’t yet available six months after its release.

What can the GeForce 6600 GT do in its AGP version? The first thing to notice is that this chip is located between the GPU and AGP slot, and is in charge of translating the AGP signal into PCI Express and vice versa. So with this chip NVIDIA is able to use the GeForce 6600 GT (which is inborn PCI Express) for AGP cards, and also the opposite as is the case with the GeForce FX.

Frequencies slightly vary between the AGP and PCI Express versions:

- GeForce 6600 GT PCI Express: GPU 500 MHz, GDDR3 500 MHz
- GeForce 6600 GT AGP: GPU 500 MHz, GDDR3 450 MHz

For the time being NVIDIA uses 2 ns memory with the AGP reference card. We believe this was a choice to reduce the fabrication costs due to HSI integration on the AGP version. We also noticed that unlike the PCI-E, the 6600GT AGP requires an additional power supply connector. The AGP only provides 40 watts to the cards compared to 75 watts for the PCI Express.

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6600 GT PCI Express vs AGP
The test
We have already done several articles on NIVIDA’s and ATI’s architecture in the past, so we decided for this article, not to do dozens of benchmarks. In this test we will compare the 6600 GT PCI Express’ performances to the AGP’s and then analyze the 6600 GT AGP compared to the competition.

The cards were tested with the closest possible PCI Express and AGP platforms. We made the test with two Intel platforms as PCI Express platforms for the Athlon 64 aren’t yet available. The test was made under these conditions:

- ASUSTeK P4C800-E Deluxe (i875P – AGP)
- ASUSTeK P5GD1 (i915P – PCI Express)
- Intel Pentium 4 3.2E GHz
- Intel Pentium 4 540 (3.2 GHz) GHz Socket 775
- 2x512 MB DDR PC3200 in 2-3-3-8
- ATI Catalyst 4.11 / NVIDIA ForceWare 66.93

6600 GT PCI Express vs AGP
As you probably already know, the PCI Express provides a larger theoretical bandwidth than AGP. So from the graphic card to the system and vice versa, bandwidth increases from 2 to 4 GB /s. Also the bandwidth is bidirectional and cumulative unlike the AGP. In practice, however, this bandwidth increase doesn’t make much difference. The AGP 4x (1 GB /s) suffices most of the time. Several graphic card and graphic engine generations will be required to really make differences apparent.

What about 6600 GT AGP and PCI Express performances? Before testing the 6600 GT we tested the 6800 GT with one of the heaviest graphic engines currently on the market, Far Cry version 1.3 at very high resolution:

In very high resolution it’s possible to notice differences, the PCI-Express version taking the lead. Performance increased by 3.9% in 1600*1200 with anti aliasing 4x and anisotropic filtering 8x, conditions under which the GeForce 6800 GT starts to show some difficulty.

Here are the results of the GeForce 6 6600 with the same resolution:

This time the performance reduction is more significant. At higher resolutions, the PCI Express version is 15.4% faster in 1600*1200 in AA 4x / Aniso 8x but neither graphic card provides sufficient results for gameplay. However, in 1600*1200 or in 1024*768 AA 4X / Aniso 8X, the PCI Express version is respectively 9% and 10.4% faster than the AGP version. Of course the fact that the PCI Express memory is clocked 11% higher is affects this result. We made several new tests with far Cry with lower frequencies for the PCI Express card at 500/450:

With equivalent frequencies, the 6600 GT PCI Express has only a slight advantage. Performance gains vary between 2 to 3.5%.

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The 6600 GT vs the rest of the world
The 6600 GT vs the rest of the world
Here are 6600 GT AGP performances compared to other AGP cards priced at $300 and above. Here again we decided not go over architecture already detailed in precedent articles. Also we used only one game, Far Cry, which is quite demanding for graphic resources including DirectX 9 effects.

Without anti aliasing and anisotropic filtering, graphic cards’ performances are restricted in 1024*768 and even in 1280*1024 by the computer’s other components. However, in 1024*768 we noticed that ATI’s graphic cards were slightly faster. Increasing the graphic resolution gives the advantage to the GeForce 6600 GT AGP, which is 7% faster than the 9800 Pro in 1280*1024 and 22% in 1600*1200. It is also faster than a GeForce 6800 LE. Compared to the previous GeForce FX, performance has significantly increased.

Activating the anti aliasing 4x and anisotropic filtering 8x is a bit of a problem for the graphic cards tested here. Under these circumstances, it’s only possible to play Far Cry in 1024*768. The 6600 GT is 5% faster than the 9800 XT and 16.9% faster than the 9800 Pro. It also confirms advances over the 6800 SE, proving that this graphic card sold at around $300 doesn’t have a good price/performance ratio and you are just paying for the name.

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Conclusion
Conclusion
With the AGP 6600 GT, NVIDIA finally offers a middle range graphic card with high performances under any circumstances. This is an improvement compared to the GeForce FX line unable to efficiently process Direct X9 effects. The PCI Express version is still the fastest, thanks essentially to a higher clocked memory. The AGP version still provides higher performances compared to a 9800 Pro, which has been up until now, the graphic card of reference for budgets from 200 to $250.

Of course, the performance gap between the 6600 GT and 9800 Pro isn’t that significant and it’s not possible to increase game resolution without performance losses. If you already have a 9800 Pro, buying a 6600 GT would be a bit useless. The 6600 GT is, however, a better buy compared to the 9800 Pro if you have $200 to $250 to invest in a graphic card. Higher performances and more capabilities thanks to a more advanced architecture makes the difference.