I'm having some trouble with suspend-to-ram. I've been on it all weekend, so maybe my thinking's in a rut and should bounce some ideas off some people.

This board is all set up with XP, no USBs currently plugged in, whatever. Thing is, it works fine in S3 STR. Sadly, it only works fine on regular desktop ATX PSUs, and only *some* desktop ATX PSUs. Does not well with OPUS ATX 120w or M1-ATX. S1 standby works fine in all PSUs tested.

Based on current input levels, I can tell that it goes into S3 just fine no matter what PSU I use. It's the resume part that gets tripped up. On the PSUs that work, the system resumes perfectly. On the PSUs that doesn't work, the system reboots on a resume attempt. I suspect some rails are dropping too low during a resume and the system loses the crap in the ram.

So, my question is this: What rails must be maintained in a STR resume? I searched online, and didn't find anything in the ATX specs. The manufacturer was emailed, but no response yet (they didn't answer an email from last month either). I've pulled the 5VSB pin on the ATX connector and had it powered 5v from a separate, constant source, but that didn't help. What else should I check?