My current PSU is a CRS MPT-301 PMC 1021A-U 33W switching power supply. It's on it's way out and I need to get a replacement. Now is there anything other than watts I need to be aware of, ie are there power supplies that wouldn't be compatible with other things on my machine? I'm fairly computer savy but not so much the stuff on the inside although I can replace stuff as long as it's the right thing (ie I upgraded the memory but needed someone else to tell me what to buy

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So are the basics of PSU's to buy a decent brand and the only thing to worry about after that is the right watts or are there other factors re motherboard, graphcs card (which I don't have) etc?
Many thanks.
Pip