Overclocking and Performance
When it came to overclocking, we had only one single issue in the very beginning: the mainboard wouldn’t start after CPU overclocking. However, it was not the mainboard, but my own mistake: I should have paid attention to the info displayed in the BIOS window on the right when I changed the parameters:
The memory frequency I set was too low, so once I raised it appropriately, everything continued smoothly. Intel Core 2 Extreme QX6700 processor (2.66GHz, 266MHz FSB, 8MB, Kentsfield rev.B3) overclocked to 3.4GHz and remained stable in several configurations:
- At 340MHz FSB with x10 multiplier;
- At 378MHz FSB with x9 multiplier;
- At 425MHz FSB with x8 multiplier.
Quad-core Kentsfield processors are usually very uneager to get past 450MHz FSB, they require significant Vcore increase. However the board itself can do way better than that: dual-core Intel Core 2 Duo E6300 processor (1.86GHz, 266MHz FSB, 2MB, Conroe-2M rev.B2) overclocked easily to its maximum of 490MHz FSB. We didn’t use the Clear CMOS button even once, because C.P.R. (CPU Parameter Recall) technology on ASUS Maximus Extreme mainboard works perfectly fine. After the first failed boot-up attempt, the mainboard restarts with safe BIOS settings, stops right after POST and offers to access BIOS to adjust faulty parameters. Moreover, the BIOS settings do not get reset to their nominal values. This is ideal work strategy for finding the most optimal BIOS settings during overclocking.
As for the performance of ASUS Maximus Extreme, there is a wide spread opinion that DDR3 SDRAM cannot compete against DDR2 SDRAM because of high latencies. It is true if your processor works in nominal mode. You will actually have to make certain effort to ensure that your system doesn’t fall too far behind the faster predecessor. However, during overclocking the situation changes dramatically. For example, the system with Intel Core 2 Extreme QX6700 processor overclocked to 3.4GHz on abit IP35 Pro mainboard equipped with 2x1024MB DDR2 SDRAM from Corsair (Dominator TWIN2X2048-9136C5D) turned out much slower. Nothing surprising about it, actually, since DDR2 SDRAM worked at about 1GHz speed, while on ASUS Maximus Extreme DDR3 was running at 1.5 times higher speed during the same processor overclocking.
Nominal frequency of Corsair Dominator TWIN2X2048-9136C5D memory is formally 1142MHz. The next divider that can be used on abit IP35 Pro mainboard during overclocking sets memory speed at 1134MHz, however the system wouldn’t run stably in this case. After a number of failed attempts we replaced abit IP35 Pro mainboard with ASUS Blitz Formula on the same Intel P35 Express chipset. I hoped that Ai Transaction Booster will help increase the Performance Level, which abit mainboard usually sets aggressively low. No luck, although replacing the board did have a positive outcome: ASUS Blitz Formula mainboard gave us an additional memory divider. For example, if we set the multiplier to x9 for Intel Core 2 Extreme QX6700 processor in order to imitate overclocking the popular Core 2 Quad Q6600, then the memory frequency needs to drop down to 945MHz on abit IP35 Pro, because it doesn’t allow setting it at 1134MHz. ASUS Blitz Formula, however, has an intermediate divider providing quite attainable 1008MHz frequency value for the memory.
As a result, Intel Core 2 Extreme QX6700 processor overclocked to the same 3.4GHz on both mainboards:
DDR2 SDRAM worked at 1008MHz on ASUS Blitz Formula, and DDR3 – at 1512MHz on ASUS Maximus Extreme.
Of course, the timings were also very different in both cases:
These were the settings when we ran memory subsystem benchmarks from the Everest suite for both systems:
Unfortunately, we failed to catch up with DDR3 SDRAM. Write speed depends on the FSB frequency that is why it was equal in both cases. Other than that, DDR3 outperforms DDr2, even in terms of latencies. The frequency difference is way too great.
Taking into account that all other components of our test platforms were the same, and the CPU was overclocked to the same frequency, we expected the system with DDR3 SDRAM to outperform the one with DDR2 memory or will run at about the same speed if the benchmark is not very memory sensitive. All in all, everything turned out exactly this way, with a few exceptions though:
For some reason, 3DMark06 CPU test puts the DDR3 system ahead of the competitor although the processor frequency was the same in both cases. We have known for a long time that this benchmark is not very valuable from the practical standpoint, however, all intermediate benchmarks from PCMark Vantage except PCMark Vantage gaming showed DDR2 system as the winner. Since there were no prerequisites for that, we have to admit that PCMark Vantage, just like its predecessors doesn’t really depict the actual situation that well.
Anyway, you should understand that we had to use and specifically configure another ASUS mainboard for it to perform as fast as ASUS Maximus Extreme with DDR3 SDRAM. Far not every mainboard working with DDR2 memory will be able to perform at the same level, and as for DDR3 SDRAM, 1.5GHz frequency is far not the maximum it can do these days. So, I assume overclockers should start paying more attention to DDR3 SDRAM.