Testbed and Methods
For our processor tests we are going to use a platform built on ASUS P5Q Pro mainboard based on Intel P45 Express chipset. This mainboard demonstrated almost impeccable stability, performance and overclockability, unlike ASUS P5Q3 Deluxe, that we have just finished testing (both review will be posted on our web-site shortly).
The complete configurations of our today’s testbed looked as follows:
- ASUS P5Q Pro mainboard (Intel P45 Express, DDR2 SDRAM);
- Scythe Mugen (Infinity) CPU cooler;
- 2GB DDR2-1066 SDRAM (Corsair TWIN2X2048-8500C5D);
- OCZ GeForce 8800GTX graphics card;
- Western Digital Raptor WD1500AHFD HDD;
- SilverStone SST-ST85ZF PSU.
ASUS P5Q Pro was tested with the latest available BIOS version 1004. All tests were performed in Windows Vista Ultimate x86 operating system.
Overclocking
We didn’t want to keep you waiting for the most interesting part of our test session, so we decided to check out the new processor’s overclocking potential first. Since Core 2 Duo E8600 with new E0 stepping is Intel’s fastest dual-core processor, it can be easily overclocked by raising the bus frequency thanks to a high 10x default frequency multiplier. However, our tests showed that our processor sample had no FSB Wall until 570MHz FSB, so you shouldn’t expect any problems when overclocking the new processor stepping using lower frequency multipliers.
During our overclocking experiments we decided to find the maximum frequency for our Core 2 Duo E8600 processor when working at its default Vcore of 1.2V.
It turned out that the new CPU has a pretty impressive frequency reserve. Up to 3.9GHz our processor remained absolutely stable. It means that there must be primarily marketing rather than technological reasons for Intel to set 3.33GHz as the default frequency for their new processor. This way Intel will be able to release even faster dual-core CPUs. However, we can hardly expect Intel to speed up its dual-core family any more considering that they focus mainly on quad-core CPUs at this time and besides, there is no competition on AMD’s part. According to Intel’s current plans, Core 2 Duo E8600 will remain the top model in the family for the rest of its life.
Our second experiment was performed with the CPU Vcore increased to 1.4V. FSB Termination and CPU PLL voltages remained at their default values.
Just like with the previous processor stepping C0, Core 2 Duo E8600 proved very responsive to voltage increase. With its Vcore at 1.4V we managed to hit 4.45GHz clock speed.
Increasing Vcore to 1.5V provided even higher results.
At this voltage setting our CPU worked stably at 4.57GHz frequency. It passed a one-hour OCCT stability test as well as Prime95 in Small FFTs mode. During this stress-testing maximum processor temperature didn’t exceed 80ºC according to the readings from built-in thermal diodes.
The frequencies we managed to achieve during our Core 2 Duo E8600 overclocking experiments indicated clearly that the new E0 processor stepping also features higher frequency potential. The Wolfdale processors with previous C0 stepping overclocked in exact same conditions to about 4.4GHz. The new CPU, the first processor on E0 stepping that we have tested so far, managed to hit more than 150MHz higher frequency.
It is very pleasing to know that Core 2 Duo E8600 will be not the only CPU on E0 processor stepping in the market. Very soon Intel will start shipping the already existing Core 2 Duo E8500 and E8400 processors with the new E0 stepping. We can certainly expect these new processors to be able to reach much higher frequencies during overclocking than they used to before.
