I am currently running the Dell optiplex 170L machine. I have upgraded quite extensively, and am currently considering fitting a new power supply. The current one is 120 watts, the one i have in mind belongs to my friend and i think is 520 watts.It pysically will fit my machine but does any one know of any issues out there that would make this a bad idea. ie i do not want to fry my motherboard, just want as we all do to run more effectively and efficiently. Any advice would be welcomed.
Tesla

Hi tesla1965, welcome to itsallPC

You must mean 220W!

Power Supply Units comply to form factor and out put standards. You system should be able to use ATX PSUs. Any standard ATX PSU will fit and provide the correct power output.

Now, I don't want to frighten you with the should, but companies like Dell have been known to implement proprietary PSU wiring that forces you to buy Dell-only PSUs. If it can't take a standard ATX PSU though, it should just fail to start altogether; no damage done.