Spongkielamot Yes, the Cooler Master eXtreme Power Plus 700-Watt Power Supply (RS700-PCAAE3-US) should be compatible with the XPS 420.  Bev.
Hi! I was hoping if someone could help me about this 700Watts PSU i research at [URL] Is this Compatible on xps 420 dell? I was planning on buying this but i wasn't sure if it is compatible. Please Suggest any GOOD compatible Power supply.. I really need som help..Thank you I currently have 375 watts of PSU -3GB RAM  -Intel Core 2 Quad Q6600 Windows 7 -1TB hard drive i was planning to get these New graphic card Asus Amd HD Radeon 6670. But i will need a help to confirm the PSU on the link below if its worth buying.. TY   
XPS 420 Power supply Upgrading