I just got a Mushkin 800 Watt Power Supply, and found that occasionally, when I turn the system off, It will shut off again a few seconds after it is started. This did not happen when I had the Antec Earthwatts 500, however, when I upgraded the PSU, I also upgraded the CPU heatsink, so everything has been disassembled, and reassembled. I REALLY don't want to have to RMA this PSU. Is there any chance that it could be something other than a faulty PSU? It does not shut off every time I turn it on, just occasionally.

It could be something else. Check the connection to see if it's tight. You may even have loosened the switch on the case cover somehow so when you press the button it actually registeres twice. The heatsink can't possibly be the cause.

I know the heatsink can't be the cause, but the fact that I unplugged and plugged every cable in the computer back in could.

Assuming that both ends of the modular cables are plugged in properly, I think I would return the unit.

I would replace it with a PC P&C silencer750 http://www.newegg.com/Product/Prod [...] 6817703009

It will also cost less. It is a tier 1 unot on this list: http://www.xtremesystems.org/forum [...] p?t=108088 I don't know about your mushkin model.