cpu pll & vcore

J

jjz-

Limp Gawd
Joined
Nov 18, 2008
Messages
302
How important is CPU PLL? I have it set at 1.88 right now, as the intel max is 1.89 and I am trying to find my max bclk.
Do I even need to overclock it? Can I just leave it at 1.8?

Also, I have my vcore and vtt at 1.4v. I am using a watercooling system with a large radiator (3x120mm fans). With a prime95 load, I run at around 78C. This is at 3.8 ghz.

I have been prime95 stable for around two hours at these settings.
Any of you guys think there is a chance I can push the cpu farther?
What prime95 load temperature should I consider my ceiling?

Thanks,

-Ian
 
Which chip are you running? c0/c1 or d0? Also, is that with HT on or off?

Seems quite hot for w/c setup. PLL has to do with the clock generator I believe, and if you're stable at 1.8 keep it that way.
 
C0/C1, HT and Turbo on. It is stable at 1.88. I have not tried it at 1.8 with an overclock.
 
It is stable at 1.8 PLL, 1.364 vcore, 1.36 vtt, 1.64v ram. This is with HT & Turbo on at 3.8 ghz (21x181).

Seems alright.
Now run at 74C loaded at all 4(8w/ ht) cores. Is this too hot?
 
i have been wondering what roll PLL plays in overclocking my cpu for a long time. Googling never seemed to help i just want to know will it help my FSB overclock and if so whats a safe limit for a wolfdale :(
 
Well, I figured out why it was too hot. I had it poorly seated. I reseated it and it dropped my load temperature 10C.
I've had to up the vcore and vtt to 1.4V though... that passed an overnight prime95.
I can't get a definite answer on whether that voltage is too high or not. Some people say 1.4V is the highest safe. Some people say 1.375. Some say 1.35. Some people say 1.55. saaya at xtremesystems said 1.6 for both.

Which is correct damn it :p.
 
I had the same trouble as you deciding on safe voltage.

I am running 1.525 indicated in BIOS. My mindset was - keep the temps good, and stay under 1.55 as I have seen that thrown around a good bit.

So far so good, but I've got the possibility of having to re-buy everything in the back of my mind, so I'm prepped if that happens.
 
With regards to max volts. I believe Intel specified that for the 45nm process volts beyond 1.45 can cause significant damage to the processor. This applied to the Penryns, I don't know if they changed anything in the materials for the Nehalems.

JJz I was going to ask if you'd seated it properly. 8 threads prime at 64 now? is quite good. If you can get the thing to run [H]ard below 70C you're good.

With regards to the PLL I've seen the really high 4.6+ OCs using 1.88 on the PLL so I don't think pushing it higher would help your OC.

Another thing to note, the 4.6+ OCs I've seen have their VTT up to 1.6V and such. This is the voltage of the QPI bus and Mem controller, which if I remember correctly is on the outer edge of the processing cores on the CPU die. Given that earlier DDR3 was operating at 1.9 and that Intel dictated a max of 1.65 for Vmem, I'm not sure it's such a great idea to have all of those values so high.

All of these factors put together will surely will make for a very hot proc, which would be very sensitive to ambient temperatures.

I guess no one really knows yet, until people start frying their procs. Remember, alot of the screenshots posted on the web are suicide runs, so to get those results for an everyday OC may be overzealous.
 
Well, my processor is idling at around 36C and load around 68C. Seems reasonable to me.
 
Much better then. Anything more than 70C I avoid. IIRC i7's have thermal shutdown at 80.
 
I believe it is actually 100C. But running them at above 73C for extended periods of time is supposed to start degrading them, or so I have heard.
 
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