I've got the i5 2400 with the ASrock Z68 Extreme3 Gen3 board. I set the multiplier to 36, left the clock at 100MHz, and booted up. Under load, CPU-Z would show peaks of 3.6GHz, but it would also randomly drop to 1.6GHz (16x multiplier). So I went back in the BIOS and disabled Speedstep, which also disabled Turboboost. Fine, I thought, I don't really need Turbo. I'll just run the CPU at 3.6GHZ all the time.
Ran another test, and I saw the same thing. CPU would randomly drop to 1.6GHz. So then I disabled C1E, "C3 state support", "C6 State Support", and "Package C state support". I have no clue what these due, but I read somewhere that they related to CPU "stepping" and should possibly be disabled to stop the throttling.
Booted back up, ran my test, and everything looked great. Solid 3.6GHz without fluctuation.
What has me confused is that I see most people suggest leaving Speedstep and all the "C" stuff turned on. Why is that? Why would you want CPU throttling?
And also, what is the end result of my overclock? Am I getting 3.6GHz on all 4 cores, all the time?