How well do the B3 Phenoms undervolt?

crabnebula · Post by **crabnebula** » Sat May 24, 2008 7:10 pm

I've been contemplating getting a Phenom X3 8450 to replace an Athlon 64 5000+ Black Edition in my HTPC, in order to unlock more post processing options with the 780G IGP.

My Athlon is undervolted and is cooled by a Ninja Mini. I'm wondering what to expect with a Phenom in terms of undervolting potential to minimize heat and noise. I'd probably underclock slightly to 1.8 or 2.0 Ghz and undervolt as much as possible.

Could anyone who has experimented with undervolting B3 Phenoms report on their findings (ie, CPU frequency, original VID & stable undervolt) to give us an idea of what to expect?

Thanks!

juamez · Post by **juamez** » Sun May 25, 2008 12:54 am

The Phenom X4 9100e is just reviewed by Tom's Hardware and runs at 1.8GHz and 1.1000V at default. They could up it to 2.4GHz while still retaining the default vcore setting. I have to mention though that the 9100e is a B2 core, not a B3, but I guess B3 can't be worse than B2.

Since the X3 uses one core less I suspect it to reach lower voltage or higher clocks than it's bigger brother. So I'm taking a wild guess here, but 2GHz at 1V may be possible. The thermals would reach ~45W spec on these settings, roughly calculated. Wouldn't that be great?

crabnebula · Post by **crabnebula** » Sun May 25, 2008 5:16 am

Thanks for the reference to Tom's. It's unfortunate that they didn't try undervolting their 9100e. Based on what I've gathered, the Phenom's seem to operate within a narrow voltage range that doesn't scale very much with frequency. The X3 has a default VID of 1.05V at its lowest multiplier (yielding 1 Ghz), so reaching 2 GHz @ 1V would indeed be great, if possible.

I've found someone who's running his X4 9750 @ 1.125V stable at default 2.4GHz, again in the same voltage range as a specially binned 9100e.