Yes they are conected the fans are spining but nothing happens. Got to run it through the on board graphic controller and when I go to device manager it only shows the intel graphic card is working. Yesterday I have changed the cpu from i5 2400 to i7 2600 it was working fine before then.
Yes, the Radeon HD 7870 GHz Edition is Windows 8.1 compatible.
Have you connected two 6-pin PCIe power cables to it from the PSU?
I am also having the same problem. 8.1 does not recognize my radeon..it is running but the only graphics card it is picking up is the motherboard. Does anyone have a solution to this problem.