do you have a brand/model # i can use to locate one?
You have a Dell. --- Dell is very proprietary, meaning other Brand Name PSU, Fans, etc will not work. Why ? Because they changed wires around or added
another MOBO contact point, so you are forced to replace with their product and not that of another vendor.
Here are some urls - You could do a search for dell PSU. And I said double the 250w, as an example. Go for the Gusto, or what your pocketbook can afford, as that 250w you have is the lowest wattage.