I believe my graphics card, after 5 years of service, has died. I want to get a new card, but what will fit in my system?  My card was an AMD Radeon R9 370 4GB DDR5 and I was pretty happy with it. I was playing COD MW with no issues until it died. Likely wouldn't spend more than $300, but if it was the only thing that fit, I could be convinced to spend more.

Alienware Area-51 R2
Intel Core i7-5820K
40GB RAM (upgraded from 8GB)
850W PSU
1TB SSD (upgraded from 2TB HDD)

I bought an EVGA GeForce 210 to see if it had actually died (I don't have any other graphics cards), but I don't have the right power connector for it (my bad for not checking).  So if anyone wants to buy it from me let me know! $30. Never used.

Any help would be appreciated.