xp-mobile / nf7-s v2 undervolting problem

[sonuvbob]

I've searched everywhere for a solution to this, to no avail. So here's my first post at spcr.

Like the topic says, I've got an xp-mobile 2400 (35w) on an Abit nf7-s v2 board, with a decent copper hsf. It'll boot at 200x8 at 1.25v, and with 8rdavcore I can lower it to 1.15v and still have 3dMark2001SE run stable (haven't tried Prime95 yet at that speed/volt, but it was stable when I tried it with other settings).

So it seems like I got a pretty good processor. However, I can't seem to boot at less than 1.25v with ANY settings- it doesn't POST and I get a repeating, alternating high/low beep from the pc speaker. After that, I can't boot until I set it to a more conservative setting than it was the last time it was stable- setting it back to the last stable setting gives me that infernal beeping again.

I've heard that the beep code means the CPU's overheating... but it's never even hit 40C- it's almost always 35-39C. Anyone know what's going on here? Any advice? Unfortunately, I don't have another undervoltable board or unlocked processor to test things with.

P.S. On a probably-unrelated note, I'm using a Sapphire Ultimate 9600xt (the passive one) that's getting RMA'd due to RAM heat problems at stock speed (little green and purple pixels everywhere in 3d, and in window title bars (gradients in win2k)) (yes, I like parentheses)

[sonuvbob]

Ok, am I right in thinking that being able to cold boot the xp-mobile at 1.1v isn't too common, and that most people start higher and go down in small steps?

[Elixer]

That's correct. My 45W 2400+ mobile won't post below 1.3 volts, so it's no suprise (to me) that you aren't able to go below 1.25V. This is a major reason why many people here are big fans of the athlon 64s; they have far more undervolting capacity. Something I've noticed is that I can undervolt it more and still have it post when just changing the settings in bios and restarting than when coming from a cold boot. Seems like processors are a bit like fans, in that they need enough voltage to start, but once started the voltage can be dropped (as long as it's not too much) and they'll keep running.

[sonuvbob]

Ah, that's unfortunate. I guess I'll have to remember to up the voltage before shutting down (looks like 8rdavcore can take care of that)

Thanks for the response