Lately, whenever I put my graphics card (8800 GTX) under stress (certain games, transcoding video etc) it will fire off its low power alarm. Most of the time it would fire once or twice and pass, or I would finish whatever task I was doing and it would go away. It seemed more persistent tonight, so I decided to boot up PC Wizard and check some things. According to that, my +12v rail is reporting at 6.92v (+3.3v is at 3.28 and +5v is at 3.6v). This seems bad to me

Before I go out and buy a new PSU, can someone confirm that I am not missing something (e.g. voltage should be are half of what you would expect due to split rails) ?

Thanks!

Split rails has nothing to do with voltage; if those readings are correct (and they might not be), your PC shouldn't be working. It's likely that PC Wizard is looking at the wrong sensor signal or misinterpreting the signal -- this is not uncommon, because of the variety of system monitoring chips. However, your original symptom of a low-voltage alarm seems plausible, so I agree that you need to buy a new (and decent quality) PS.

It sounds like a motherboard issue reporting false voltages, if the 12v rails fall below 11 instability of motherboard/hardware components will occur, it is awfully low readings on the 12 & 5 volts which supply the HDD and dvd drives and some older motherboard processors, each rail works rather independently of each other, I may suggest purchasing a antec power supply tester, not sure what the model # is but it has the diagnostic lights, or a simple resistive type which plugs into the ps, a voltmeter and knowing the voltages of the red, yellow & orange wires, if the computer runs stable, its likely false readings, hope that helps

Since Pc is working readings are probably false. But if You get a low power alarm from nvidia drivers You should be looking new psu. Check voltagers in BIOS. Or use a multimeter . Not knowing other specs I would recommend Corsair VX550. That is what I have with overclocked CPU, 3HDD, 2DVD-RW, 5 case fans and overclocked 8800GTX. If You are not overclocked and less peripherials in Your PC VX450 should be fine as well.

go ge a DMM and check it, this is the only way to check voltage accuracy

^+1. The software voltage reporting are (90% of the time imo; excluding vCore) are in accurate. Like he said get a multimeter and check it out. (lol, SpeedFan reports my +12 on my 450VX as 1.2v lol)

The system would not even run that way, ignore it.

Concur with the above Posts, WITH some minor exceptions. As stated your software is giving you invalid readings. HOWEVER the low power alarm is cause to suspect the PSU and needs to be checked And most likely replaced.

1. Manuf specs for the +5 and +12V are normally +/- 3 %, Max exceptable is +/- 5%.

2. On software – Any reading that is way outside normal (And PC is working) is INVALID. You might want to try CPUID. CPUID also provides current values and min/max values which is useful for comparing idle vs loaded values On my system all voltages are valid when compared to a DVM (Very minor differences noted )

3. I always recommend using a DVM (multimeter) – They are easy to use and a low cost one can be found at radioshack. For the +5 and +12 simply measure the red to black and the yellow to black on a Molex connector. Compare readings at both idle and under load. Also you can then correlate these readings with “software reported values. One of my minor exceptions – multirails are NOT independent, they are normally feed from a single source and contain separate current limiting circuit. A failure in this circuit, a bad connection or excessive load on a specific rail is about the only reason for significant variation in voltage between rails.

4. PSU checkers are useful for checking a PSU before use, You do not want to put a defective PSU in that fancy new build! But they are very limited on verifying outputs when under moderate to heavy load

True. I should have thought of that lol.

@OP: What PSU are you using?

I was using an Aerocool Zerodba 620w. Read some more reviews on newegg and it seems that others have had failures with them and the company was no longer accepting warranty returns for that model. Went out today and picked up a Corsair 620hx after reading several reviews. The voltage reports are exactly the same through PC Wizard and the siren alarm still fires off of my GPU (confirmed it is my 8800GTX that is making the alarm).

I called BFG Tech support (amazing service, if you are in the market for a new card) and they are sending me a new one. He suspects that my sensor is defective in the GPU as it is just a hardware switch that fires the alarm. After bumping my RAM voltage from 1.85 to 2.1, the alarm will even briefly sound on boot, when the card isn't even under load.

I'm hoping that the new GPU sorts this all out. All that said, I'm glad I grabbed the Corsair PSU as it is a much nicer design than my old one

Just curious, Did you download CPUID to see if it provides a more accurate readings.