Low I/O voltage - motherboard or PSU?

[XMan]

The 12 and 5 volt rails are fine, but the 3.3V for I/O is only 2.5. The 3.3 is derived via step down on the motherboard, isn't it? Or is the PSU bad?

 

[Zepper]

I assume you are getting your Voltage readings from the health chip. I would measure with a DVM before worrying too much, as long as things are working OK. It would make sense if the I/O voltage came direct from the PSU as there is too little differential between 5 and 3.3 for efficient regulation. The higher the input/output differential on a regulator, the more stable and efficient it is.
.bh.

 

[XMan]

Well as far as worrying too much, the system isn't stable and the voltage warning siren keeps going off.

This is on an NF7 2.0 with a 3200+.

 

[Zepper]

Well I'd still want to check it with a DVM so I would know for sure (a DVM is something any home should have anyway, and a good enough one is available in most areas for $10. or less). But if the system isn't stable, go ahead and get a new PSU. Threre are plenty of discussions in GenHdwr and Cases/Cooling about which brands are best. If you don't have a heavy AMP sucking video card or a slew of drives, a good brand 300W PSU should be plenty.
. I would try to borrow a known good PSU just to be sure it is the PSU. If you need to order one, the the Enlight 360 is pretty good for $35. shipped or the Sparkle 300W "FSP300-60PN" at $36.
.bh.

 

[daveybrat]

why don't you tell us what model of power supply you are getting this with?

 

[XMan]

It's an Enermax 351 that worked perfectly fine in a P4 system. I pulled it to replace it with an Enermax 431 and stuck it back in the box for a couple of months, then re-used it in the AMD system.

 

[XMan]

It was the motherboard.