Help! :)

I just brought a EVGA GTX 970 for my pc and when I tried to install the drivers I got a drivers failed to install message. At first I just assumed that it was because my old drivers were just uninstalled incorrectly so used driver sweeper to completely remove them. This also didnt work and now I am stumped at what to try next.

My build is - Motherboard- Gigabyte H81M-D2V
Processor - I5-4570
2x 4gb Kingston
PSU- Cool Master RS-500 PCAP-13 500W
Old GPU - GTX 760

Also after the 970 was not working I thought I put the 760 back while I asked some guidance and now the drivers for that wont install, I am unsure what to do next. Is my PSU powerful enough for the 970? Should I wipe the pc completely to make sure it is not a driver problem?

Cheers guys :)