i had bought a powercolor amd/ati radeon hd 7750 1 gb gddr5 gpu but when i plugged it in the monitor didn't show any display.So my question is was it a problem of the gpu or its something related to my power supply which is 250 watts.Should i buy a new psu or will it work?Thanks for the answer.
Agreed. 250w is too low, you'll need a 400w minimum, although I normally suggest a 550 to 650w PSU. It depends on your budget and your plans for upgrading. A 550w to 650w PSU will save you money in the long term. :-)