GPU Not Installing on PC

Hi, I purchased a Gigabyte Geforce GTX 1650 to upgrade my pc to 4k, the GPU did not install once fitted, so I upgraded my power unit to 750W, but again the graphics card didn’t load, my system is running a intel i7 CPU 870 @ 2.93. board DP55WG, any suggestions on why not working? or alternative GPU’s that I should purchase… FYI for media not gaming…