Sorry for bumping this thread. I know its a couple of months old, but I have the same issue.
NF7-S v2.0
Athlon XP2800+
Hiper Type R 480w ATX12v v2.0 PSU (Supplies no -5v)*
Patriot XBLK PC3200 DDR
I'm was sure I had seen readings of -5v in BIOS, MBM5 and Speedfan, but looking at the MBM5 "High / Low" Log it has always recorded -5v as being between +3.50v and +3.55v so my memory could be playing tricks on me.
Speedfan reports the same values for the -5v line as MBM5 (+3.55v approx)
BIOS reports the -5v line as being -61.99v (Which I'm sure I would have noticed right?)
Measuring with a multimeter between PSU Comm (Black) and the back of the "absent" -5v line at the motherboard/PSU power connector I actually really DO see +3.3v So it would seem that Speedfan and MBM5 are correct.
All the other voltages are pretty much within tolerance, though the PSU does seem to get warmer than my other Hiper 525w which has 3 fans. But really it is no warmer that the case temp as reported by the motherboard sensors. (PSU temp measured at PSU exhaust vent and very top of PSU enclosure with digital thermometer.)
I ran the system up quickly with a Q-Tec 500w PSU which DOES provide the -5v line (see my note below regarding ATX PSU's) and all readings in BIOS etc were as you would expect them. This was only a test though and I dont recommend anybody use a Q-Tec PSU for anything, ever.
My conclusion.
While I cant really explain the presence of the +3v potential between Comm and -5v pin on motherboard it is actually likely that the -5v is really not used on this motherboard and the BIOS reading is simply an error. An alarming looking sort of error but quite probably not important.
My system runs stable at stock, and has been stress tested with Prime95 for almost a week with a mild overclock (multi x11, FSB 200, v-core 1.675v)
Recently I have been experiencing increasing instability with this OC which has not yet been resolved but is just as likely to be cooling or BIOS related as it is to be Voltage stability or indeed any -5v functionality.
Hope this makes sense.
Obviously any and all comments regarding this subject are welcome.
* ATX12v v2.0 specification does not have to include -5v This is a "Legacy" voltage which was apparently for ISA bus support. Modern motherboards (including the NF7-S) do not have an ISA bus. I have read in several places that the ISA support was the only function for the -5v line and have not yet found anything that indicates it is neccesary in any way on the NF7-S
While some manufacturers seem to include the -5v anyway (probably to make them backward compatible in the case of more expensive brands and simply because it would require a PSU redesign rather than "modification" of existing design in the case of much cheaper brands.) It is notable that neither of my Hiper PSU's supply this voltage.
