Sempron 3100+, undervolt & microATX

Weiman · Post by **Weiman** » Tue Oct 12, 2004 3:58 am

I'm in the process of upgrading my HTPC and I want something that doesn't run much hotter than my current Celeron Tualatin 1200. I've been mostly eyeing the XP-M 35W 2400+ along with a Biostar M7NCG-400.

But along comes the Sempron 3100+ which looks awfully tempting. Question is, can it be run nearly as cool as the XP-M? Using undervolting and a little underclocking if necessary. Is there any suitable microATX motherboard that allows undervolting?

/Johannes

Jan Kivar · Post by **Jan Kivar** » Tue Oct 12, 2004 12:59 pm

Well, I can run my A64 3000+ 1GHz@0,85V. Some people are running their A64s even lower speeds (this is actually the lowest setting): 800 MHz@0,8V.

The best part is that it's claimed that any board with nForce3 chipset is able to do this (depending on the capabilities of the CPU, however). There are some mATX boards, at least from Gigabyte and MSI.

Welcome to SPCR!

Cheers,

Jan

silvervarg · Post by **silvervarg** » Tue Oct 19, 2004 4:40 am

If you go for an XP-M the 2500+ Barton seems to be highly regarded and priced very attractively.

The faster Sempron with the Athlon 64 stripped seems very interesting as well. Since it has not been out that long not many builds have been done by SPCR members yet, but personally I have high hopes for this chip.

Bean · Post by **Bean** » Tue Oct 19, 2004 9:48 am

I've been mostly eyeing the XP-M 35W 2400+ along with a Biostar M7NCG-400

I did this combo and liked it. BUT the board's lower limit on the CPU vcore is 1.300 however the FSB is entirely adjustable. My prime95 temps: antec aria,120gb spinpoint samsung and slk900 7vpanaflo @11*166,vcore1.32,amb28=46C 10*166vcore1.3=41. Scared me once when temp shot up to 50C while sufing the web for10-15 min. (not very long). I quickly shut down and found the CPU fan not working.

If you get a board that will use the bus disconnect/stop grant built in to the k7, they seem to offer the lowest power usage at idle. I dont think nforce2 boards will allow this but the via boards do ( someone correct me if I'm wrong).

just saw this interesting chart comparing idle and load power usage of the 3100 also K7, K8 and CelD, P4. unfortunately it doesnt have the k7 at anything less than 1.5v (interpolate possibly) but the 3100 sure looks impressive. http://www.goodwin.ee/sulo/Power2.htm

But along comes the Sempron 3100+ which looks awfully tempting. Question is, can it be run nearly as cool as the XP-M? Using undervolting and a little underclocking if necessary

I suspect the answer is yes. Plus for HTPC, you get the sse2 support if that helps with your application.

Weiman · Post by **Weiman** » Tue Oct 19, 2004 11:24 am

Thanks.
I guess the new Athlon 64 3000+ 90nm would be an even better choice, but unfortunately there aren't any microATX motherboards with S939 available yet (or even announced AFAIK)..

hvengel · Post by **hvengel** » Tue Oct 19, 2004 3:27 pm

¨If you get a board that will use the bus disconnect/stop grant built in to the k7, they seem to offer the lowest power usage at idle. I dont think nforce2 boards will allow this but the via boards do ( someone correct me if I'm wrong). ¨

This is not totaly correct. The following BIOS´s will work:

KT133/133A
KT266/266A/333
KT400/KT600
SIS730/733
Nforce
Nforce2
AMD751/760/761 but not 760MP

All of these can be enabled in Linux with a simple command line hack which is different for each BIOS. But only a few are supported in Windows with the existing cooling software. I have and AMD760 MB and I use VCool in Windows and the command line hack (in /etc/init.d/boot.local) in Linux. I know that VCool will not work with the Nforce2 BIOS. VCool and the Linux command line hack work well and are stable on my system. This results in an idle temp that is about 18C lower than with out the bus disconnect/stop grant enabled.

At idle with the disconnect/stop grant enabled CPU power consumption is reduced power to about 5 watts. But of course power useage does go up as CPU usage increases and is that same at 100% as a MB without bus disconnect/stop grant.