Undervolting Ci7 920

[Mr. Pedantic]

I have a C0 Core i7 920. When I got it I proceeded to overclock it, and I got to about 3.6GHz with a voltage bump I was happy with.

However, seeing as how Uni has started again and I don't game anymore, and the fact that the CPU is overkill for everything else I do, I've decided to underclock it.

I've put everything back to default except the BCLK, which I've set at 150 (to give me 3GHz). This is the highest the CPU would go on stock voltage, 151MHz on stock voltage would not even POST. However, it's perfectly stable at this speed.

I tested this for about 6 hours with LinX, and then decided to drop the CPU volts one notch. It now loads at 1.240V according to CPUz:

http://valid.canardpc.com/show_oc.php?id=1077374

So far at this voltage it's completely stable, no errors or anything. Are there any caveats I should watch out for when undervolting? And should I try drop other voltages as well? How much effect does the memory and QPI voltages have on power draw?

 

[qazwsxokmijn]

My D0 920 does 3.8GHz at 1.246v. I think a C0 doing 3GHz at 1.24v sounds about right or a tad high.

 

[SunnyD]

3.33GHz i7 920 D0 @ 1.056v here. "Pretty much" stable, had a BSOD the other day, but it's the first ever on this build, and I'm not entirely sure what it's from.

 

[aigomorla]

3.33GHz i7 920 D0 @ 1.056v here. "Pretty much" stable, had a BSOD the other day, but it's the first ever on this build, and I'm not entirely sure what it's from.

if u have windows 7 check out the event viewer.

Sometimes it tells you what hung the system.

 

[Mr. Pedantic]

I've had suggestions from other forums about disabling hyperthreading as well, so I'll probably do that when I get home from uni. But otherwise do I just keep stress-testing and decreasing Vcore?

My D0 920 does 3.8GHz at 1.246v. I think a C0 doing 3GHz at 1.24v sounds about right or a tad high.

According to my MSI Eclipse 1.24V is 20mV below the stock voltage already. And the CPU isn't stable at 3.8GHz or above, no matter what volts I put through it. I'm really envious about people with D0s, I bought my i7 just a few weeks before D0s came to market.

 

[Interitus]

Do you have Speedstep or any of the power saving features enabled?

I'm not sure how those features figure in reduced clock and/or voltage for power savings, but if you're undervolting anyways, you might want to disable them to see if it improves how low you can go on the undervolt. Of course this is pretty pointless if you're going for max power savings, but if you're aiming for a stable low voltage point for normal use even when loaded, it's worth a try.

I've never owned a C0, but my D0 is a beast. Made it all the way to 4.1 on stock voltage. I might try and undervolted profile for daily simple tasks soon too. I assume since it goes so far forward with no voltage increase that it would go the opposite way pretty well too.

 

[Mr. Pedantic]

Do you have Speedstep or any of the power saving features enabled?

Yes. I enabled Speed-step and Turbo just after my initial underclock; they seemed to decrease stability heaps when I first did my OC'ing, but at the moment they don't seem to have much impact.

I've never owned a C0, but my D0 is a beast. Made it all the way to 4.1 on stock voltage.

Lucky, lucky you. I'm so jealous.

 

[Interitus]

Yes. I enabled Speed-step and Turbo just after my initial underclock; they seemed to decrease stability heaps when I first did my OC'ing, but at the moment they don't seem to have much impact.


Lucky, lucky you. I'm so jealous.

Speedstep gives me nothing but trouble. The system hangs because it tries to run at full tilt at around .9v. Strange.

WTH. I figure I didn't buy an i7/x58 rig to save on power Running at 4.1 on stock is insane, but even with high end air, I'm battling to keep it cool. VREGs are scorching. Seems like they're getting all the CPU heat dumped onto them and that little EVGA mini-tower cooler isn't tall enough to benefit from the CPU fan (with a tower style cooler anyways). Debating trying a small fan on it, but I've heard a lot of mixed results with that.