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Dropping PLL for overclocking.

DrSteve

DrSteve

DrSteve

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Sorry if this has already been posted but came across this on another forum. The poster suggests that lowering the PLL voltage below standard is adding stability at lower vcores when overclocking. May give it a try myself and see if it makes any difference.

Link
 
This is interesting. I set my rig at 5.4GHz with my normal settings and then dropped PLL right down to 1.65000v without any affect... I'm not convinced that dropping vcore maintained stability but just the PLL drop did affect temps.
 
I did this on my previous i7 920 D0....I was able to drop Cpu Pll all the way down to 1.4v from the default 1.8v, with no adverse effect on my overclocks. I'll certainly be trying the same with my 2600K.
 
Down to 1.7v on the PLL at the moment and it's been running an hour of Prime blend, stable so far and seen drops of 3-4c!

4.5ghz at 1.34v
 
I had a play with this during the day.

At 4.8GHz I am able to run PLL at 1.7000v without issue. Once I go above 4.8 I really need to put it back up to 1.8 or even a little higher.

I did a 20 minute Prime 95 run at 4.8GHz first with PLL at 1.8v and then for a second time at 1.7v (I did not find I could change vcore so that stayed at 1.3v). I left RealTemp running throughout the tests (Reseting the Min/Max inbetween) and in both cases the Max temp reached was 70c. So I saw no difference in temps. I must point out that my CPU fan is on the MB CPU header and controlled by the bios using silent mode.

So my findings are that it did not really improve either my max overclock or my temps. That said it is always good to have lower volts where ever possible, so nice find and very greatful for the info.
 
SimonMaltby said:
I had a play with this during the day.

At 4.8GHz I am able to run PLL at 1.7000v without issue. Once I go above 4.8 I really need to put it back up to 1.8 or even a little higher.

I did a 20 minute Prime 95 run at 4.8GHz first with PLL at 1.8v and then for a second time at 1.7v (I did not find I could change vcore so that stayed at 1.3v). I left RealTemp running throughout the tests (Reseting the Min/Max inbetween) and in both cases the Max temp reached was 70c. So I saw no difference in temps. I must point out that my CPU fan is on the MB CPU header and controlled by the bios using silent mode.

So my findings are that it did not really improve either my max overclock or my temps. That said it is always good to have lower volts where ever possible, so nice find and very greatful for the info.
Click to expand...

I wonder if the voltage you are using to stay at those speeds is kind of masking the temp effect?

I've just run prime for 40 minutes at 1.8 and am now running again at 1.75 so i'll have a look see what the temps are like. Hopefully the lower pll might allw me a little room to either lower my vcore at 4.5 or get a bit more out of it upto 1.35
 
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Mine did indeed run stable at 1.7v last night for 6 hours. I'll be trying to drop it further over the weekend.

As far as temps go I recorded at 1.8 and at 1.75 using CoreTemp and took an average of the last 20 readings. The average was within 0.5c on each core. I'll be keeping an eye to see if they do affect the temp in any way as i go lower.

I'll also be having a a play to see how far i can go on the vcore now. With a 1.8v pll I got a BSOD if i tried 4.5ghz @ 1.27v after about 3 seconds.
 
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