ATI Radeon hd 5770 compatible with my computer intel dh 55tc?

Ati Radeon hd 5770 is not working on my intel DH 55 TC ,,,, but other graphic cards are working fine ...|||Did you uninstall the other graphics drivers for your older card, before installing the 5770? You need to uninstall the old drivers, uninstall the card, then boot up and install the newest ATI drivers from the AMD website... Your computer will reboot between the uninstall and the install of the drivers, so don't be alarmed for a reboot...