Idiots guide to undervolting? (help with a q9550)

stephentw · Post by **stephentw** » Tue Apr 21, 2009 5:54 am

Well, I'm not really an idiot. But this undervolting stuff is mildly confusing. I've read a few threads saying people have managed to keep their CPU at stock speed (which is what I want) and undervolt to aout 1.1-1.2 does that sound like a realistic starting point?

Also should I be just changing the VCORE? Or should I start fiddling with ram and other things too?

I'm aware I should also stress test afterwards, with prime95 I think I read? How long should I look to leave this sort of thing running to determine stability?

Thanks.

yamahaSHO · Post by **yamahaSHO** » Tue Apr 21, 2009 6:59 am

I undervolted just the CPU voltage down to 1.032v with an OVERCLOCKED Q9300 (@3Ghz). What you can do is lower the voltage and see if the computer boots up. If not, raise it in small increments until it boots. Once it boots, run a stress test for a couple hours to see if is stable.

lm · Post by lm » Tue Apr 21, 2009 7:05 am

Don't the CPUs of today automatically idle at some low voltage and frequency? What kind of savings are we looking at with Q9550 at idle?

ntavlas · Post by **ntavlas** » Tue Apr 21, 2009 8:07 am

1.032 @ 3ghz is quite low, lower than the idle voltage set by speedstep at stock speeds. Which motherboard did you use? I smell gigabyte...

lm · Post by lm » Tue Apr 21, 2009 10:40 am

yamahaSHO wrote:Once it boots, run a stress test for a couple hours to see if is stable.

More like +24h... it's common enough to get errors from prime95 only after several hours.

aristide1 · Post by **aristide1** » Tue Apr 21, 2009 3:24 pm

ntavlas wrote:... I smell gigabyte...

I prefer the smell of souvlaki myself.

lm wrote:
yamahaSHO wrote:Once it boots, run a stress test for a couple hours to see if is stable.
More like +24h... it's common enough to get errors from prime95 only after several hours.

That would be 1 Prime95 per CPU.

yamahaSHO · Post by **yamahaSHO** » Tue Apr 21, 2009 3:37 pm

I ran it for about 8 hours (while I slept at night) and it had no errors on my setup. I've been using it since then (October) and haven't had a problem. You can run it for 24 hours, but if it's stable for 4 hours or so, I'm sure it will be fine.

aristide1 · Post by **aristide1** » Tue Apr 21, 2009 4:28 pm

I've had failures after 20 hours, but if you're not folding you're OK.

stephentw · Post by **stephentw** » Wed Apr 22, 2009 3:01 am

Thanks everyone, sounds good. I'll give it a go when I get my new fan and psu.