Dell optiplex gx620

[ihavenoc]

So I just bought this dell OptiPlex gx620 with ATI Radeon HD2400 XT 256MB Video Card on ebay. but the graphics suck for world of warcraft, I tried installing my ASUS grahpics card but when I turned the computer back on it was flickering in green

 

[Kisianik]

2 questions: first what Asus card you have and second did you try this Asus card on WOW on the other PC? Your PSU could be weak for this card, so gave us your specs: CPU (model please), PSU (wattage, or is this original?), RAM and exact model of GPU.