Overclocks Not Registering?


Doc, I’m trying to overclock my Core 2 Quad Q6600 from its stock speed of 2.4GHz to 3.5GHz. But when I set the overclock and boot back into Windows, nothing shows the overclock as working. The OS as well as CPU-Z show 2.4GHz on my Gigabyte GA-EP45C-UD3R board. I’m running RAID 0, 4GB of G.Skill DDR2 RAM, and Windows Vista 64-bit.

—Al Stein

First, you’re asking an awful lot of a Core 2 Quad Q6600 on air cooling. It is a great overclocker considering its stock speed of 2.4GHz, but you probably should not expect to push it to 3.5GHz on air and see great results. What you may be seeing is Intel’s SpeedStep throttling the CPU back when it isn’t under load. Just to make it clear, at stock speeds, your CPU uses a stock front-side bus of 266MHz on a 9x multiplier for a total of 2.4GHz. Since you have no option of doing a clock-multiplier overclock (because the multiplier on your Q6600 is locked), you are likely running your front-side bus in the region of 395MHz. On a 9x multiplier, that’s about 3.5GHz. The SpeedStep on that processor will actually crank back the clocks by lowering the multiplier from 9x to 6x. It just so happens that a 6x multiplier on a 395MHz bus is about 2.37GHz, which the OS may round to 2.4GHz. To test this theory, put a load on the CPU and see if the clocks move up.

SUBMIT YOUR QUESTION Are flames shooting out of the back of your rig? First, grab a fire extinguisher and douse the flames. Once the pyrotechnic display has fizzled, email the doctor at doctor@maximumpc.com for advice on how to solve your technological woes.

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