The Mother Board

[Rudurk]

[Karlsweldt]

Computer power supplies (the PSU) do pack enough power to kill someone.. if the discharge path is across the heart! Two large capacitors in the primary circuit store up to 250 volts DC, which is lethal. DC voltages can freeze body muscles, causing temporary paralysis. AC voltages can cause body muscles to tighten and relax quickly, and thus may cause you to release your contact. But not always!
Safest way to work on a PSU is to remove the AC power cord, and attempt a few starts before removing it. Let it sit for about 1/2 hour, to ensure the primary voltage reserves have dropped to near zero. Then it is safe to work on.
As to repairing a PSU, not worth the effort. Regulation circuits may be damaged by bad caps, and may then damage the rest of the system.
Going with a good brand of PSU having more wattage than needed is a safe bet. For the few dollars extra, you get a better product. A PSU will never "push" more power than needed.. only provide what is required.
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F@H.. to solve mankind's maladies.. in our lifetimes!