|What have you done so far? |
Does you motherboard have an on-board graphic?
If yes, connect your monitor to that connector if possible.
Power down and remove power cord.
Extract the Radeon card and power on. If the system boots up, power it down again, remove power cord, insert firmly the Radeon card again. Connect monitor to Radeon card and power on.
Is there a reason to install Win XP?