Effects of PLL Voltage?

Arachnae

Arachnae

Arachnae

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Can anyone tell me what it does?

Also, how it affects overclocking, is higher better or lower better?

I've been doing some research on it but there's no clear answers I've found, just values people use :(

I'm aiming for a 4.2Ghz overclock just to see if I can do it really.. and my voltages trying to get it seem very high, will increasing my PLL help this at all?

I'm not sure I'm remembering the numbers exactly here but rjk said I should be using around 1.92 aka the first yellow number, but then i've seen people saying that it's crazily high and I should drop it down.

So, what's the real deal with it? :)
 
PLL voltage directly effects FSB and is the most likely voltage adjustment to kill a CPU. 1.92v seems very high but without knowing the rest of your system specs/setting I can't say for sure.
 
pll voltage effects the phase locked loop, and thus stabilises the clock pulse. generally a higher voltage means it can 'lock in' to the desired frequency more efficiently (governed by the oscillator x multiplier)
 
Well it's an i7 920 on an asus p6t se board, 6 gigs of ram..

im hoping to get it at 200 BCLK for a 4.2ghz with turbo.

then my ram will run at proper speed too :) im currently pushing 1.35V on my processor and qpi and its still nto stable.. thts with my pll at the lowest available though.. im wondering if raising it will help me get the clock speeds.

It seems a lot of people on here are able to get 4.2 but are strained by temps, i seem to be strained by volts :(
 
It seems ( depending on individual chip ) that 4.2ghz and over the PLL needs to be adjusted. I would not think its possible without a little help. With the info provided by weescott about what the PLL is for , I would tread carefully. For 6GB though (3x2GB) i would not think it needs to be that high. ? Max i would say is 1.85 - 1.90v.

What is your QPI/VVT voltage ??
 
i read on here somewhere that apparently lowering the PLL on i7's seems to give better results?

try experimenting, just don't put it too high as that will cause damage.

check the intel spec sheet for your chip too as this will show you intel's specific limits
 
McstylisT said:
It seems ( depending on individual chip ) that 4.2ghz and over the PLL needs to be adjusted. I would not think its possible without a little help. With the info provided by weescott about what the PLL is for , I would tread carefully. For 6GB though (3x2GB) i would not think it needs to be that high. ? Max i would say is 1.85 - 1.90v.

What is your QPI/VVT voltage ??
Click to expand...

I believe the QPI is at 1.35V

Curently my pll is at 1.80, first yellow value is 1.92
 
Raising PLL on the x58 platform, for the main part, causes instability.
As has been said, most peeps run with it at at about 1.45v/1.65v as it is the sweet spot when clocked around 4ghz/4.2ghz.

The only time you should need to raise the PLL is when you are running very very high Uncore (over 4000).
 
These numbers you guys are giving me seem rather odd..

The intel spec sheet on the i7 says the voltage minimum is 1.71, typical is 1.80 and max is 1.89

However another part of the specs sheet says that its absolute minimum is 1.65..

It's all so confusing :/
 
I think so too. My board's minimum is 1.80v. When at 4ghz stable it was still at 1.8v.

If your going to play with the PLL , do it safely. In theory you should not need more than 1.85v , but as you mentioned do not go over 1.89v. Every chip is different and some need extra help than others.

Also just been reading in another thread that some 920's require as much as 1.4v to achieve 4.2ghz. You seem to have covered all the other settings to no effect so maybe raising the Cpu voltage slightly will help. Personally 1.4v scares me long term though.

McT
 
It just seems odd that on my board, 1.8 is the lowest manual value you can put in, and only at 1.92 does it go yellow.

I'm wondering whether my lower PLL (i lowered from 1.92 to 1.80 when someone said it was stupidly high) is stopping me from hitting the higher clock frequencies?

As an aside, perhaps the values i can choose from include a base voltage or something?
 
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Arachnae said:
Well it's an i7 920 on an asus p6t se board, 6 gigs of ram..

im hoping to get it at 200 BCLK for a 4.2ghz with turbo.

then my ram will run at proper speed too :) im currently pushing 1.35V on my processor and qpi and its still nto stable.. thts with my pll at the lowest available though.. im wondering if raising it will help me get the clock speeds.

It seems a lot of people on here are able to get 4.2 but are strained by temps, i seem to be strained by volts :(
Click to expand...

Mine does 4.2 @ 1.2750 VCore, CPU PLL = Auto and QPI DRam @ 1.325.
After 20 runs of LinX, CPU Temp went to 72 and Max Core Temp is 88C.

I think you need to lower the VCore and try setting the PLL to auto and see if it help improves stability.
 
I think my chip might be a bit pony and trap! :(

I set everythign to auto at 4.1Ghz and the system sets the core to a whopping 1.42V :/

using 195 x 21

Any idea if something like 210 x 20 would be better than 200 x 21 or maybe even 222 x 19?
 
unfortunately 20 x 210 doesnt boot at all, and 222 x 19 freezes in windows :(

I did managed to get a stable 4.2ghz but its with 1.42V.. much higher than i want to go at...
 
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