Really?? I have a 9800gt on another computer and It calls for a 400watt or greater. I dont want to burn up my psu.
Yeah. The 9800GT without a power connector can even only theoretically use 75w because that's the limit of the PCIe port.
Those cards are under clocked a bit however so they are slightly weaker than what you see in the chart dragon posted above. Another factor to consider is the case, Dell uses some funky ones so make sure how many slots the card can take up and how long it can be before making a purchase.