So recently I've purchased a Supernova G3 650W to replace my old PSU that isn't delivering the power it needs to sustain my system.  It's been a long time since I've installed a PSU but I've not had one act so problematic out of the box.  It's stable now but for the first boot the computer restarted with power button press and it's been spontaneously rebooting for the next few cycles (both with and without resetting the PSU).  I'm just wondering if this is normal?  I might reseat the connectors if the problem persists, but it seems OK for now.
 
No, I did not test the PSU with the included tester.  Also the 3.3V registers at 3.2V and dips to 3.18V under load.  Don't know if I should be concerned.

Well, according to the box it says "extremely tight voltage regulation [1%]"
so I ask because in that case all three (5, 3.3 and 12) rails fail.  I'm going to return it because it failed the shutdown ATX command and usually when that happens I don't trust power supplies.

ketxxx
I'm guessing you used software to monitor the rails? Software is rarely 100% accurate so best to take its reading with a pinch of salt. I'd also reseat all connections ensuring no dust/grime has got on the connections and also remove the power cord from the back of the PSU, then press the power button 3-4 times to completely discharge the capacitors. You should now be good to go. If not it might well be worth returing the unit if the problem persists you know the issue is elsewhere in the system, I'd start by checking the RAM modules are seated correctly and the gold connectors aren't dirty.

I used both software and the BIOS, however I think it meant that under load the voltage it has doesn't deviate between load and idle.  So the 3.2V remaining 3.2V means its within 1% tolerance.
 
Strangely the store I bought it from just stocked the 750W version and is cheaper than the 650W, so I replaced it and haven't encountered any problems.

What is your system load generally?

even the bios is not 100% accurate, the only way to get the true reading is with a good meter, not the $19.99 special from the local store but a true RMS from fluke or similar company

QuintLeo
DC voltages, no RMS meter needed except to read the AC line input.
A GOOD accurate meter however is a requirement, so the Fluke should still apply.
 

the true RMS meters are the higher quality ones and very accurate. my fluke was $500 but you get a real nice one for around $200