I have a E8400 processor running on a Gigabyte EP45-UD3P motherboard. The processor is "rated for 3.0GHz" but seems to default to 2.66 out of the box. I though I would check my computer's performance with it running at the rated 3.0GHz. However, the temperature increase at this speed didn't justify the marginal performance boost. I've since decided to run the processor at 2.83GHz. I've adjusted (in the BIOS) the multiplier to be 8.5x (8.5 multiplier * 333.3 bus = 2.83GHz). Also, the The BIOS setup currently shows the processor running at 2.83GHz (As expected). However, Windows Vista (in the System control panel applet) shows it running at 2.66GHz. Using CPU-Z, I see that under load, the processor is running at 2.83GHz with a 8.5 multiplier, but during rest, the multiplier drops as low as 6.0x (due to the processor throttling function enabled in the BIOS). Why does Vista report a different processor speed than is actually set? -Ryan Adams Free Computer Tips and more:http://RyanTAdams.com Paid Tech Support: Black Diamond

1. your CPU is designed to run at 'at least' 3.0GHz. If you're temp isn't good at the speed, check your cooling setup...something's not right. BTW, what is the temp that you're finding unacceptable? 2. your CPU is underclocking at idle or under light load because you apparently have Speedstep (EIST) enabled in the BIOS. If you want it to run at full speed at all times, simply disable SpeedStep. I don't know why Vista is reporting the speed differently.

I should have been more clear. My rig isn't running "too hot", it's still well within reason. However, the increase in temp going from 2.83 to 3.0 is exponentially more than going from 2.66 to 2.83 while the performance boost was marginal at best. Yes, EIST is enabled, and that is fine with me. All my games play fine, and I'd rather save some power and heat when I am just sending emails and such. My real concern is why Windows reports a processor speed different than what it actually is. It doesn't make sense that Vista reports the CPU as 2.66GHz when CPU-Z and the BIOS both clearly report it is running at 2.83GHz. Is this some sort of bug in Vista? Does Vista perhaps calculate the speed by taking the FSB and multiplying it by the multiplier and not recognizing the 0.5 multiplier increments. -Ryan Adams Free Computer Tips and more:http://RyanTAdams.com Paid Tech Support: Black Diamond

I still would have liked to have seen the temp just to know what the increase is & what you're considering unacceptable. I know if it was my system I'd disable EIST & clock the CPU at 3.2GHz (8 x 400MHz). If the CPU didn't idle below 40C, I'd adjust the cooling config, not the CPU settings...but that's just me. I just found the following article but it's over a year old: E8400 temperature If you enter something like vista reports cpu speed wrong into Google, you'll find a lot of info about Vista misreporting the CPU speed.

Hey , i have the same problem. I have a e8500 on a gigybyte EP45-UD3P motherbord. however the cpu is only running at 2.17ghz when its ment to be at 3.16ghz? its a good rig and it defently isnt overheating as i have a antec 902 . What can i do ?