Power first. Does the PSU have the wattage and the right PCIe plugs? A strong card on a weak supply means random shutdowns.
Space next. Case length, slot width, and whether the CPU and board can feed the new GPU without becoming the new bottleneck for your games.
Then value. Sometimes selling the whole PC and moving to a balanced system beats stacking upgrades on an old platform. Send current specs and we will be straight either way.
Not sure what you need?
Pick a path, run Find my PC, or message with your games and budget. We will keep it practical.