Monitor will not pick up signal from video card?

my video card has been working fine for a year and a half now, had to recently change out the power supply and immediately after my monitor will no longer pick up signal from the computer for more than a second. you can tell it knows when the computer is being turned off and on but i get nothing more than a blink of change. tried another monitor and same thing happened. must video card or perhaps i screwed something up replacing the ps. help.|||If PC does not BEEP once after powering ON, it is not booting at all that is why there is no video signal to monitor. Check the 4-pin 12V connector (yellow and black wires) to motherboard to insure proper fit. Also try resetting CMOS by removing CMOS battery on motherboard for at least 30 seconds then put it back. You must do this while PC is UNPLUGGED.