Mechanical fits.
Has the same or more power plugs.
Opt for a single +12V rail.
HOWEVER, Dell's 320 Watt PSU may rival the usual 20 buck 500 Watt PSU so I would not count on it delivering more than the stock unit. In fact if I want a long life PC I add up the Watts, double it and that's the total Watts I look for in my new PSU. I also avoid multiple rails on the +12V unless I have the time to add up the Amperes on the +12V rail then the same rule. Double that.
Bob
Hi. I have an older dell e-520 with the original 320 watt power supply. Because of the number of periferals and other upgrades I have on ths comp, I'd like to put in a larger power source. I'm thinking about 450 -500 watts. Since I've never done this before, I mean I can handle the installation and all , but what should I be aware of and look for when I go looking for the new power supply? Is there anything that might jeopardize the system I already have? The computer has one of those next to useless Pentium D processors. Is there anything that I need to match to the new power supply, or install with it? Thanks, any insight you can give me is greatly appreciated.

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