I've just built a new system and installed vista. In the bios, which is the latest one available, I have the multiplier set to 9 and the bus speed to 266 which would give me the standard speed of 2.4Ghz.
CPU-Z is telling me that it is set to a multiplier of 6 and bus speed of 266 giving me 1.6Ghz. Now the bios I downloaded was considered a beta and I'm wondering if I should go back to the one previous to the beta.
However this is a little confusing because under "Specification" CPU-Z reads "Intel Core 2 CPU 6600 @ 2.40GHz" and my PC reads that the CPU is running at 2.4GHz.
Its one of the options in the Gigabyte bios. I had the same thing happen to me the other day, it basically scales down your clock when its not under load, to minimize heat/power I assume. If you place a load on it you will notice that it goes back up to 2.4GHz as it should.
I forget what the name of the exact option is called, but its something in the M.I.T i think. If you disable it you will run at 2.4GHz all the time.
It's under Advanced BIOS settings - turn off 'CPU EIST Function'. Might as well turn off 'C1E Enhanced Halt' as well while you're there. Go read these instructions if you plan to overclock the processor, and they include turning Speedstep (this function bothering you) off. http://forumz.tomshardware.com/hardware/Core2Duo-Overcl...