ProcessorsFor this test we have received 3 desktop Core 2 Duos:
X6800 (2.93 GHz, FSB1066, 4 MB L2) : $999
E6600 (2.40 GHz, FSB1066, 4 MB L2): $316
E6400 (2.13 GHz, FSB1066, 2 MB L2): $224
The three processors have reached the stepping 4, B0 revision. Processors in stores will be in stepping 6.
The motherboard : ASUSTeK P5W DH Deluxe
Tests were made with the ASUSTeK´s i975X + ICH7R motherboard that supports the Core 2 Duo, the P5W DH Deluxe. There are also the usual functionalities implemented via this chipset, as well as ASUSTeK´s additional functions.
First of all for storage, one of the 4 SATA port supported by the ICH7R is connected to a Silicon Image 4723 chip that split this port into two. So, it´s possible to connect a single disc on the first port that will be used normally, or two to use them in RAID 1, RAID 0 or JBOD. To choose the two latter modes you have to change the jumper position. RAID 1 is initially configured which is rather antiquated. ASUS also integrated a PCI Express JMicron JMB363 controller. The latter supports two Serial ATA (including one external), which can be configured in RAID 0 or 1, and one additional UDMA 100/66/33 port which won´t be too much for some users as the ICH7-R only supports one.
Network management is entrusted to two Marvel 88E8053 chips. Supporting the Gigabit network, they are interconnected to the rest of the system via PCI Express. There is also WiFi as the card has a WiFi 802.11a/b/g Realtek RTL8187L chip that uses the USB bus. HD audio is entrusted to a Realtek ALC882M chip and the card is in accordance with Dolby Master Studio specifications. FireWire is supported via a Texas Instrument controller. We noted the presence of an infrared remote control that switches the computer on and off, placing it in sleep or silent mode or even controls the sound level or video displayed.
First off, we took a look at power consumption of these processors. The Core 2 Duo is derived from Mobile architecture so it has the required base for low consumption. Fabrication process and low dissipation transistors, the Core 2 Duo benefits from the latest fabrication process that reduces electronic dissipation. SpeedStep is of course implemented and has, according to Intel, been improved for the reduction of transition time.
A new power management method exists in the Core 2 Duo that allows the processor to accurately manage consumption even in load. This is called, Ultra Fine Grained Power Control. It consists of a very precise cutting out of areas that can be placed in sleep. Non solicited units remain in sleep even if the others run at full speed. This often happens, because it´s rare that all processor units are solicited at the same time. This ultra precise management makes it possible for better control of power consumption and thermal dissipation.
The last innovation of the Core architecture that aims to reduce processor power consumption is the capacity of the data and address bus, which are capable of adapt themselves to the length of data. So if only 64 bits have to be processed, only half of the 128 bit bus concerned is activated.
What difference does this make in practice? Here is the total power consumption of the configuration in load under Prime 95. The software is launched as many times as the number of core as it isn´t multithreaded. For the Athlon 64 X2 and FX, measurements were taken on the M2N32-SLI Deluxe with AM2 Socket:
Results were very good since the Core 2 Duo E6600 and E6400 are less hungry than the Athlon 64 X2 3800+. Strangely enough, power consumption of our E6400 was equivalent to the E6600 despite an identical voltage of 1.3V. The Core 2 Duo X6800 also doesn´t have a high power consumption, because it´s barely above the Pentium 4 631 at 3 GHz, whose performances of course are at a much different level.
We are far from the power consumption of the FX-62 and especially the Pentium D 950 (here in stepping B1). Based on a 90 nm fabrication process, the Celeron has a higher power consumption than the 65 nm Pentium 4 631.
What about Overclocking? Of course our processors are "only" stepping 4, but we wanted to know what was possible. For each of the following results only an air cooling systems were used, in fact here the standard CPU cooler sold by Intel with the Pentium 4 & D. Room temperature was 31° for these tests and we increased voltage by +0.1V. Only results of overclocking with 2 Prime95 for 15 minutes was included in our results.
The E6400 goes up to 3.2 GHz. However, at this frequency the FSB is 400 MHz for the ICH7, while we had to increase voltage to 1.65V.
Our E6600 didn´t give us the same good result, because stability was impossible at 3.2 GHz despite a voltage of 1.4V.
Finally, the X6800 was the most overclockable with stability reached at 3.4 GHz and 1.4V. Once again, we have to specify that overclocking was only valid for stepping 4 Core 2 Duo. Stepping 5 apparently easily reaches over 3.4 or even 3.6 GHz with air cooling. Starting with a too low clocked processor requires a high FSB not necessarily supported by all motherboards. For example, for 3.6 GHz, a E6400 will require a FSB of 450 MHz. Indeed, for the coefficient part, it is possible to reduce steps from 1 to 6 whatever the CPU is thanks to the EIST. We couldn’t reach over the basic coefficient, however, even with the X6800.
Overclocking Step 5
Just after finishing all tests, we received a stepping 5 Core 2 Duo E6600 and tested it to see what the Overclocking potential of this processor was. The conditions were the same:
This time, the 3.4 GHz were stable from 1.35V as compared to 1.4V for the X6800 step 4. We even reached 3.6 GHz in 1.4V. To go over this, voltage needed to be increased even more and the processor starts to dissipate a quite a bit of energy. Water cooling solutions will be greatly appreciated.
Aiming for a frequency between 3.4 and 3.6 GHz seems to be perfectly reasonable for a Core 2 Duo stepping 5.
Performances at 3.6 GHz
What are the performances of a Core 2 Duo overclocked at 3.6 GHz in 9x400 with DDR2-800 and timings of 4-4-4-12 ? This is what we wanted to know. Here are the figures compared to a X6800 in DDR2-800:
With a 22.7% frequency increase, we could logically expect similar performance gains, sometime even higher, because of the impact of a more important FSB in some of the tests.