I am stumped, and quite frankly about to give up. I'm running an i5-760.
Out of the box I set it to 3.6GHz and 1.15v (1.075v in CPU-Z), disabled turbo, and left everything else default. My RAM was running at 1440 and 9-9-9-24-2T (below stock). I ran small FFTs for 6 hours, max temp of 53c, everything was fine. I played some Bad Company 2 for a couple hours with no issues.
Today I decide to push it a bit further; I set it to 4GHz and 1.3v (1.2v in CPU-Z), RAM was at 1600 and 9-9-9-24-2T (stock), Small FFTs 6 hours, max temp 64c, stable. I start BC2, it freezes my comp 15 seconds after loading my save. I try again, blue screen. Try once more, crash to desktop. I put my clocks to where I had them the previous day and everything was fine again.
That was two hours ago. Since, I've tried everything I can think of to get it to work at 4GHz. I upped some voltages, lowered my RAM multiplier to set them to 1200 while keeping my processor at 4GHz, fidgeted with some other BIOS stuff; the game simply won't run at anything above 3.6GHz. Unfortunately I have no other games to test, and won't for a few days.
TLDR: 3.6 stable in Prime95 and BC2, 4.0 stable in Prime95 but NOT BC2, temps are fine, I tried a bunch of stuff and am out of ideas.
1. What gives? I fail to see how Prime95 could be stable for hours, but less than a minute of a game causes freezes, blue screens, and crashes.
2. Would the increase from 3.6 to 4 even be noticeable? Unless it would net me a 10-15% increase in frames, I'd rather have the lower power consumption and temperatures.
Well, you can't play at 4.0GHz, so there's no frame rate increase right now.
-- You've added the GPU functions and data transfers with the game's engine, prime95 doesn't care much about the GPU, just the CPU and RAM - that could be the reason prime95 is stable and the game is not.
-- I don't know if the +.4GHz would be noticeable, but all of us want to hit 4.0GHz, stable.
-- You may be able to get it working @4.0GHz by loosening your RAM, maybe only the second latency setting (I don't know why, but sometimes bumping up the second latency one or two can make the RAM stable).
-- If your BIOS allows, you could also try increasing the CPU voltage to 1.35V or 1.4V
i run my phenom 955 be at 4.0ghz from 3.6ghz and had 6fps difference in bfbc2 on 9800gtx+ get 45fps max detail 1920x1080 resolution 2xAA
maybe you should test at lower clocks or raise the voltage on cpu a bit thats what i did. and i know my system is amd but should work for yours too.