I think this might work

[mythbuster74]

Will this card work in a Dell e521

ECS N9800GTE-512MX-F GeForce 9800 GT 512MB 256-bit GDDR3 PCI Express 2.0 x16

http://www.newegg.com/Product/Product.aspx?Item=N82E16814134066

 

[obsidian86]

305 Watt DC Power Supply in dell e521 most you could hook up to that is a 4670