Dell? watch the physical size.
If renewing a PSU check:
1. The physical size of your PSU, some are hard to replace due to being a non standard size.
2. The amount of power need from the PSU don't skimp
1. Physical Dimensions
Besides the specs and form factors, the physical dimensions are also important factors in selecting a compatible power supply. Here is an outline of the physical dimensions of most standard power supplies:
# ATX: 6x3.5x5.5", HxWxD. Most common. Uses 4 mounting screws.
# Mini-ATX: 5x3.5x5", HxWxD. Rare size. Uses 4 mounting screws. Can be used in a regular ATX case, but often not the other way around.
# MicroATX: 5x3x4", HxWxD. Use 3 mounting screws. Not interchangeable with ATX or miniATX.
# Flex ATX: Even smaller than Micro ATX. Various sizes according to case specs; often not interchangeable.
Use the data above to determine if a particular power supply would fit your case.