Have you tried connecting to the hard drive using an alternative SATA slot on your motherboard ??
then have you tried using a different SATA cable ?
If this fails try connecting your hard drive to an alternative computer then write back with results :D
If you don't have an alternative...
I happen to like being a blueberry best years of my life was at the academy... One time me and the rest of the CSO'S decided to get smashed at the kavala bar and we ended up handcuffing another CSO and leaving him strapped to a lamp post naked in kavala square.
The best method to all series of fault testing is firstly find out if the fault is software side ....
i.e install a fresh copy of windows and if that doesnt work
the issue is hardware side :D
Unless you know where to look hardware wise id suggest putting it in a shop otherwise ...
£200 quid you can get a GTX 980 at that price and trust me you will never have to upgrade for atleast 5 years will run everything in ultra settings
No point in buying one of these new 1000 series cards unless your looking to run your games in 4k.
Another good option is the 780TI older series...