Keen comment App103 as you easily forget to do so, when synchronizing software and/or data from the main PC to the backup PC is done.
Nudone, are you sure the PSU works fine? Does it supply the intended voltages (+12 Volt, +5 Volt, GND, -5 Volt, -12 Volt) within the margins set by the manufacturer, does it still put out the specified Ampere? Seeing a "pilot" light on the mainboard coming up does not mean that the power supply (reliably) works.
You would be terrified about the amount of power supplies that I have here which appear to be working, but really are not up to the task anymore. For fun's sake, I did count them and there are 14 of them lying around here. The sad reality is that Paraguay has a lot of power failures/spikes/noise which results in a lot of prematurely dying power supplies.
Getting powerful, high quality ones did not pan out. They didn't really last longer than the cheap ones and with the huge price difference I rather replace for another cheap one. Which occurs quite regularly given the amount of faulty PSU's here.