Did you undervolt the videocard? Did you check temperatures while mining, with Gpu-z or HwInfo?
You may have damaged it...
Remove other cards and plug this one directly on the motherboard, PCI-e 16x. See if it boots and displays the desktop at least. Then see if it shows as VGA or AMD Radeon
i am mining from 3 months with it never got any problem like this before and yes i have checked temp it was 77 degree ! And how can you say that mate it is damage ?? the Gpu fan is working fine !
And yes i have removed it and inserted in another 16x slot but in device manager it's not showing ! other cards are working fine !