There are various wires/cables that connect my PC power supply to the motherboard, hard disks, etc. If I replace the power supply can I just disconnect the existing cables from the current power supply and connect them to the new power supply or will the new power supply have its own cables that need to be used to connect it to the motherboard, hard disks, etc.?
A couple of other questions.
Do the mini-tower PCs use the regular size power supply or do they use a smaller one?
Which cable extension should I purchase to extend the existing power supply fan speed monitor connector cable? It comes out of the motherboard whenever I remove the power supply (to work on it) and it is very difficult to put it back in.
1a) Generally no, but in some case's it's possible, as long as you're talking about a modular power supply
2) Depends on the case
3) A 3 pin male to female fan extension cable
Haven't seen a fan cable on a psu since the Antec TPT, meaning you most likely have an older power supply, meaning that the chances of reusing your cable's is very slim.
Providing the make and model of the components will get you a more direct answer