I'm positive that's a power supply unit problem.

bucksavage wrote on 12.05.10 at 02:29:20:


I think it's either your AC current supply from the mains socket or powerstrip that's dodgy after the power outage, or your PSU must have gotten a bump after a blackout/brownout. What I would do in your situation is get a cheap multimeter and test the powersupply 3.3, 5 and 12v+ rails to see exactly if the power is stable.

Do this when you get the weird power issue.

To easily do this unplug every wire from mainbord, VGA, HD, drives, and only leave a few fans attached.

Switch off PSU by rocker switch on back of PSU.

Jumper the green pin and any black pin on the ATX power connector with a piece of wire. I use a paperclip.

Then power up the PSU. The fans should turn on. Now insert your red probe into a yellow or red wire on any molex (12 or 5v), and your black probe in a black wire, do this in this order, do the reverse of this when you take em out. Check to see if they deliver stable voltages, they shouldn't fluctuate and should be around the 12 or 5v mark.

Do the same for the brown wire on the ATX plug (3.3v)

If all this checks out allright, plug everything back in. And now when PC is fired up do the same thing. Also check under heavy load scenarious such as Furmark/3DMark to see if the rails are still stable.

If they are stable, it could well be your motherboard. Sometimes if your mains supply is unstable due to situations beyond your control ie. powerboard/grid defects, they can do damage to your electronics.

If your powergrid is dodgy, it's best to get a powerstrip that filters your powersupply, or even better a USP, uninterrupted power supply, basically a big battery that which lets you save your work in the even of a powerout and lets you safely power down.

Hope that helps.

bucksavage wrote on 13.05.10 at 07:13:23:


Stange that it's just running fine normally. I would suspect it to be the mains?

No a dead CMOS battery just forgets the settings, the machine will boot up and says CMOS defaults loaded.

Just thought I'd post a little update on this as I recently installed a program that monitors temps, cooling and power.  For my PSU, these are the power reating as of right now: 
+3.3V standby - between 3.317 and 3.352
+5V - betwwen 5.026 and 5.052
+3.3V - varying between 3.180 and 3.214
CPU Core (+1.85V) - between 1.8 and 1.812
CPU I/O - (1.5V) - between 1.471 and 1.484

Would these be within tolerance?

Tim wrote on 12.05.10 at 14:27:02:


Very good post and I suggest that OP look into how his/her local grid functions during load ans spikes knowing that it has a big impact on every thing drawing power from it. My grandmother spent 12 years building high voltage stepping transformers so i got to see some of what takes place there. They are vulnerable to emp and solar flares that can cause spikes in the lines that can overheat the coils with in the transformers and storms often cause dips and spikes. The worst case is when there is a momentary spike that causes permanent failure of the grid till the damaged infrastructure is repaired.

Forgot about using software to measure your rails. They are so off the mark it's not funny anymore. The only accurate way to measure them is by multimeter.

elfuego wrote on 06.09.10 at 19:46:30:

I'm not that well versed in doing this kind of stuff, but, if I do check it, I'll make use of all the advice given here.  Thx everybody.