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PLL voltage

twist3d0n3

twist3d0n3

twist3d0n3

Soldato
Joined
3 Aug 2008
Posts
10,477
Location
Bath, England
hi guys, i've got my e8400 up to 3.93GH, and want to squeeze that extra bit out of it, and was wondering what is a safe PLL voltage? i've had a little read on it, and as far as i've found out increasing this can 'clean up' the clock pulse making the CPU more stable. can anyone confirm if i've got that right??

system as in sig

cheers
 
Ok Quick Answer:
1.5v - 1.6v is fine

Long Answer:
You are correct, PLL standard for phase locked loop and basically works by taking the input waveform and generating a new waveform that locks its phase to the incoming wave form but with a multiple of the frequency. Out of sync frequencies can effectively generate "noise" that can cause the clock to become unstable
 
Last edited:
up to 1.6? wow... i had mine on 1.5 until the other day where i thought i'd try a small increase to see if that would help with stability - i went to 1.52 and thought 'please don't die'! sweet, i'll bang it up a few more notches and see if i can hit 4.2 :D

cheers
 
just had a read on XS, and from what some of the guys on there were saying, my FSBT was too high, so i've dropped it to 1.2v, taken the NB down to 1.26v and upped the PLL to 1.56, and it booted into windows (which i really was expecting). All in all, got a lot of voltages down (extremely happy about that) and it still boots.

now all i have to do is stress it and hope it'll do a few hours in orthos :D
 
pastymuncher said:
You should be increasing the vcore not the PLL voltage. What vcore are you using? Don't go above 1.45v for a Wolfdale.
Click to expand...

PLL does sometimes need to be increased, especilly if you are running high vcore and vtt

although yes I do agree he should be looking at vcore and vtt as well.. but had assumed he had fiddled with these seeing as he was looking into PLL
 
i've set vcore to 1.335, and upped the NB to 1.36.

does vtt = fsb termination voltage? if its not i haven't seen it in bios..

i read the data sheet for e8400 C0, and it said 1.36 was the safe limit, although i presume intel are just being cautious with that figure.

cheers
 
FYI

Don't exceed the following voltages for 45nm

Vcore = 1.45v
VTT = 1.3v
PLL = 1.6v

CPU degradation will result if you do and kittens everywhere will suffer a painful death.



...ok the last bit was a lie but the rest is a good guideline;).
 
1.45? hmmm, might have to put some more volts through my core then :P

before today, i had vtt @ 1.37 :S hope i didn't do any damage...

cats suck anyway, bring on the cpu degradation :D
 
Well intel quotes the max vcore and max vtt both as 1.45V.

However, I've not needed over 1.26VTT ever anyway
 
after a bit of fiddling last night, i've ended up with:-

4.01GHz
Vcore 1.3625
PLL 1.56
NB 1.31
Dram 2.10
vtt 1.26

orthos lasts for about a second lol

any ideas how i can get this stable?

cheers guys
 
twist3d0n3 said:
after a bit of fiddling last night, i've ended up with:-

4.01GHz
Vcore 1.3625
PLL 1.56
NB 1.31
Dram 2.10
vtt 1.26

orthos lasts for about a second lol

any ideas how i can get this stable?

cheers guys
Click to expand...

Your NB volts are way too low especially if your running 4gb of ram. I have a similar setup and need the following for 4ghz
Vcore 1.304v - cpu-z
PLL 1.55v - everest
NB 1.65v - everest
Dram 1.9v - everest
vtt 1.26v - everest

Steadily increase your NB voltage and test again with orthos watch your nb temps and use an extra fan on it if they get a bit toasty, mine stay under 50 with a 120mm fan on the NB, hope that helps.
 
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