So I have my Core i7 920 overclocked to (4.0 GHz) on 1.256V. Clocked any higher and Turbo Mode seems to throttle down from 21x to 20x multiplier after some P95 stress testing. I've tried upping the Vcore and VQPI with no luck. It seems the throttling is based one core temp. If my cores exceed and sustain 68-70 C (or higher) it seems to drop down to 20x.
Has anyone one else faced this issue? Is temp the culprit or do you think there are other voltage settings that may be saturating and causing the throttle?
in my opinion, anything past 4.0 on that CPU would show very minimal gains and only risk damage or reducing the life of that CPU.
If it were me and i could hit 4.0 with no problems, i would try to see if speedstep worked with that overclock, and disable turbo-boost. This way, you won't have to worry about the prospect of harming the CPU and when idle, it'll throttle down to save energy and the life-cycle of the CPU...
Though if anyone else reads this, would you agree that anything over 4.0 on a 920 is overkill and not worth the risk?
Indeed, i know what you mean, but here's a similar situation, my Q6600 is @ 1.39 VCORE and running 3.6 fine, temps peak @ 65*cel average 55*cel and idle @ 34*cel, now when i up the voltage to 1.41 & bring it to 3.8, temps fly to 75*cel, average 63*cel & idle @ 50* cel
So, again, to me, it is not worth the small gain that i get (maybe 1-3% performance) going from 3.6 to 3.8
If you really want to test it and see if it'll be harmful, turn off turbo and OC it to 4.3, see what the temps hit.
My guess here is that @ the voltage you have set, turbo is attempting to boost but not liking the voltage or heat and thus throttling down...
Yea I know what you mean. But even when I was at 4.2 GHz with temps around 72-74 C it's throttling to 20x (20x 200 MHz = 4.00 GHz, which is about the same as 21x 190 = 3.99 GHz) The second one (4.0 GHz w/Turbo) uses less Vcore and thus temperature. So I figure it's smarter (more efficient) to run 21x 190 than 20x 200.