Hello, I have a Dell Inspiron 545S. I need to know the best high-end graphics card that is compatible: both with the small case and the power supply. Will the Nvidea GT 240 or GT 250 or the Radian HD4670 work?
You have 2 problems working against you. The 545s is a slim case needing a low profile video card and the power supply is only 250W.
GTS 250 exceeds the power reqmts your system can provide. EVGA recommends a 450W power supply for it's GTS 250s.
I'll take a look around and see what might work for you.
Have you check the Dell support forums? You should be able to find what other 545s owners have used to successfully upgrade their own systems.