I bought the xfx hd radeon 5750 with a new power supply. I installed the PSU, and it works fine. Now when I try to boot up with the graphic card plugged in it does not show any video with the monitor plugged into the card or onboard video. If I plug the card in after boot it turns on fine, but there is still no video. The xfx installation disc cannot detect the card and says the boot back up with it plugged in and try again, which obviously doesn't work.
Check for previous drivers (Nvidia, or older Ati ones) and then un-install it and make sure none of the files are in your PC. Try to Re-install the ati 58xx driver with catalyst, ect.... then update it. Perhaps another simple mistake is that you plugged the DVI into the 2nd port or even the motherboards DVI accidentally and you may be using your onboard GPU..... its possible....
I am having the same issue, got a 5750 for Christmas and just got back home to install it. Upgrading from a radeon x1950 pro to this, and when I uninstall the drivers, turn off my computer install the new card(yes, connecting the power cable to it- I made that mistake switching back to the x1950 to write this message and my monitor actually displayed a message saying that was the problem.) nothing happens. The card gets power, light on it and the fan are going, but my monitor just says no signal and goes into idle mode. I have no idea unless I've got a bad card. Any help would be appreciated.
Does your motherboard have SLI capability, if so try plugging it into another port.
Also try removing all unessential things. So remove everything except the motherboard and video card and see if it loads up.
It may have power issues as well. So the card is not getting enough power.