That was just after boot-up with nothing running, idle.
It's actually flucuating from 11.58-11.71v idle/web browsing. The PC shutdown while playing a game (first time it's happened). I ordered a Corsair 450w, but it's not likely to be here before the end of the week. Should I take advantage of a stores return policy and swap one in until then? If I don't game, what do you think the chances are of it going out before next week?
It's actually flucuating from 11.58-11.71v idle/web browsing.
As randomizer wrote, the PSU is within +/- 5%, so you probably won't be in trouble unless the voltage drops below 11.4V. Try getting a game running and then hit the "Start" key. This will temporarily take you back to the desktop and you can get a reading on the volts, temps, etc from Speedfan. That said, if you can swap out the PSU for a better one, it might be a good idea. Another thing to consider is that though Speedfan is a good indicator, the reading you get in the BIOS is a better one.
Can someone tell me where on speedfan it shows your +12v rail?
When I open speedfan it shows the +12v as 0.38v and the -12v as -16.97v.
Not sure which version of Speedfan you're using, but I use version 4.31. On mine, the 12V is the lowest lefthand position in a box at the bottom. If you're only showing 0.38V on the +12V line, either you have a very bad PSU or the install of Speedfan went bad. Since I really doubt your computer would turn on with only 0.38V on the 12V line, I suspect that the install is bad.
As an aside, the reading I get on 12V line is 11.84V, about 1% low.