HP EliteDesk 800 G1 TWR GPU Compatibility?

iViscosity

Commendable
Jul 1, 2016
15
0
1,510
One of my brother's boss sold me one of his old PC's for $200, which is an HP EliteDesk G1 TWR. Specs:

OS: Windows 10 Pro 64-bit
CPU: Intel i7 4770 @ 3.4GHz (Quad-Core, Haswell)
RAM: 32.0GB Dual-Channel DDR3-1600 (I think) (4x8GB)
GPU: Intel HD Graphics 4600 (Integrated)
GPU2: nVidia Quadro 600 (1GB)
Motherboard: HP 18E4 (Haswell)
Chipset: Intel Haswell 06
Storage: Western Digital WD10EZEX-60M2NA0


Now, as the title suggests and as the specs suggest, I'm looking to upgrade my GPU. My brother was going to let me use his old GTX 650, but the PSU didn't have the correct wires(?) for it, so he tried to use his old PSU with it (450W) but the motherboard didn't support it (sorry, not the greatest when it comes to the inner workings of PCs), so now I'm stuck with the Quadro. I was wondering if any of you brilliant people would be able to help me, as I'm wondering what graphics card I would be able to slap on this thing to be able to perform better. I'm looking for a gaming GPU (which is why I want to get rid of the Quadro) and I can also get a stronger PSU if needed (currently it's only 320W). I'm not sure how to check if a GPU would be compatible with the existing motherboard, so I came here for help. I tried to give as many details as possible, but please let me know if you need any more.

Note: I'm not looking for anything too intensive, my most intensive games are probably Overwatch and Skyrim, which don't take monsters to run afaik.

Thanks for any help in advance!