Voltage and overclocking question

[Guest_Jim_*]

In light of the new 3DMark contest (good luck everyone) I'm going to try to overclock my machine a bit more. Currently I have my AMD 720 with 4 cores unlocked at 3.41 GHz with a multiplier of 15, a bus speed of 220, and a northbridge multiplier of 11. Through all of this I've never touched the voltages in the BIOS and left it all on Auto. So now I would like to set my voltage to something constant, either higher for a better overclock, or to just where I need it for this overclock, increase Auto has it higher than needed.

According to CPU-z and AMD Overdrive, which will log the voltages, the current voltage is 1.392-1.393 on average (the max AOD recorded was 1.42). I've got an H50 with push/pull fans and the temperature is staying around 59C, with a Prime95 blend stress test in the background right now, so temperatures are fine.

Here's my question, where should I first set the voltage and what would be the best process for increasing it.

 

On a vaguely related note, how should I overclock the RAM? That is the only thing I've ever tried changing the voltage on because no matter what I've done I can't get the 1600MHz it can do. When I try setting the BIOS to use 800MHz for the frequency instead of 667MHz, it always crashes and refuses to boot with that setting. I'm thinking this issue is more the motherboard than anything else, so I'm not too worried about it.

Thank you all that help.

[Drdeath]

Your maxed for voltage. You cannot increase your temps any more as you are at max. You need a better cooling solution.

[Guest_Jim_*]

Actually the voltage can go higher and the cooling is fine. The max voltage according to AMD is 1.425 and the max temperature is 73C, neither of which I've hit and it is possible that the motherboard is pushing the voltage higher than it needs to be. What would be the best process for stepping down that voltage then, to determine what it should be?

[wevsspot]

Hi Jim.

 

For me there are two ways to go about determining how much voltage is needed for a certain overclock without over volting the processor needlessly.

 

My first step is extensive online research and reading to try and find out how much voltage other overclockers are using to reach certain overclocking thresh-holds. If you get lucky you might find entire thread topics or even databases showing overclock results at certain voltages. Once I have an idea of how much voltage a certain processor or family of processors requires to hit specific overclock ceilings I start on mine.

 

That begins with setting my processor to the stock voltage setting specified by the mfg and from there I start overclocking until I have hit the ceiling of the frequency the processor will run at stock voltage. I always underclock my RAM at this stage to make sure that it doesn't hold me back until I've found the max overclock I can run on my processor alone. Once you've found the ceiling your processor can achieve at stock voltage, then you need to bump your cpu voltage up a small amount (say .02V) and rerun your stress tests. My cpu stress testing consists of Linx, OCCT or Prime95. You can choose one, or any combination because sometimes one type of stress test will fail, when others pass. The key here is to run the stress test long enough to really push the system, your cooling, your power supply etc. Prime95 I always run for 8 hours minimum. OCCT I run for 4 hours minimum. LinX I run for two hours minimum.

 

If you pass stress testing at one voltage you can increase your cpu frequency until you fail testing. Then you bump your cpu voltage again and re-run the stress test(s). This process is repeated over and over until you reach a point where temperature or over voltage becomes an issue. Those pain points vary from user to user and depend largely on the efficiency of your cooling solution and your willingness to accept risks.

 

Once I've found the max overclock I'm willing to run based on temps and voltage, I always back it down a tad for day to day operation. Keep in mind that an overclock that seems reasonable during the winter months when your ambient temps may be lower, might not be the same overclock you would want to run during the summer when ambient temperatures are higher. I live in a part of the country where the summer months get over 100F and the winter our temps can drop down into the teens.

Edited August 23, 2010 by wevsspot

[Guest_Jim_*]

Thank you wevsspot, though must I undo the overclock, or could I try to find the voltage for what I've got, following the same procedure you've described? Also, I know through AOD and CPU-z what the vcore is on average and at maximum, so, if I may start at the current overclock, should I search around those first?

[ebarone]

You can always try using an Asus overclocking utility from within Windows to step back the voltage until you BSOD. That would give you a good ball-park kind of idea as to where to set your BIOS voltage, and go from there.

[Guest_Jim_*]

You can always try using an Asus overclocking utility from within Windows to step back the voltage until you BSOD. That would give you a good ball-park kind of idea as to where to set your BIOS voltage, and go from there.

I forgot about that tool! Sadly though, it isn't proving that useful. It let me get the voltage down a fair bit, but the BIOS won't. Well, at least I've got one thing going for me; Prime95 crashes real fast without the right voltage, so I don't have to wait that long (I'm a little impatient).

[Guest_Jim_*]

How much should the measured vCore differ from the value set in the BIOS, or is the BIOS just a maximum? The BIOS is set at 1.45, but after 16 minutes of OCCT the voltage, according to Asus PC Probe II, doesn't appear to have crossed 1.4. Is the BIOS just the maximum the CPU can draw then?

Also, looking around online, people appear to have been getting the same frequency (though with multiplier alone and not multiplier and HTT speed as I have) but with a lower voltage. I see them at around 1.41-1.42. Is that still near enough to be expected, or is something else going on.

This is why I've never messed with the vCore before, because I know a lot less about it than maybe I should.