Originally posted by ropey
A rail is a line that supplies the voltage to power devices. You have a +12V rail, a +5V rail and a +3.3V rail.
The specs on your PSU are:
+3.3v @ Input 28A
+5v @ Input 40A
+12v @ Input 18A
Are these correct? Open your case and look at the PSU's specs. Are they the same as this? Turn your computer off and remove the 4 screws that connect the PSU to th case. They are at the back of the case. Do not remove any cables. Just lift the PSU and test the weight. Then replace it and the screws.
I would watch these rails very carefully as the specs are not always what they seem with a value based PSU. They will easily either destabilize your overclock or even damage your system if taken past its ability.
A simple way to test the PSU is to lift it and test its weight. If it is very very light then you need to get a better one or do not overclock very deeply. This test is not enough to test how good a PSU is but it is a decent way to test whether it is bad. There are NO good very light PSU's.