Wow, that's an old card! I bought a GPU in 2010 and it was a 5770! I still have it!
Is your GPU included in your liquid cooling loop? If yes, then it'll be a pain to take it out. Then you'll have to decide if you want to water-cool your next GPU; if yes, you'll need to buy a water block for it and reconfigure your tubings. If no, you'll still have to reconfigure your tubings.
If the GPU is not included in the loop, things are much easier. Just buy a new GPU, take your old one out, plug the new one in, install the new drivers, and done!
Might be best to post pics of your tower setup here but if you didn't assemble your PC and you've not dealt with liquid cooling loops before, it might be best to have someone else do it for you instead of risking damaging your setup. A quick GPU swap might be the least of your problems if things go wrong.