Well, the 1080Ti is old. So you'll need to buy them used. I'm a big fan of watercoolong. Machined my own CPU block around the turn of the millennium, years before the first commercial products were available. Then spent more than 20 years without owning a desktop.

It's not hard, really. Watch a lot of YouTube builds. Ignore the shiny ones and focus on the low cost ones. Also watch videos about how real corrosion looks like and how discoloration from using colored coolant looks like, and videos about how to open and wash/clean blocks and how to wash/clean radiators.

As for the build: No hard tubing. I like PVC soft tubing (aquarium tubing) because it's very cheap and very easy to work with. The fittings I get from aliexpress. Bykski, Barrow, Freezemod, etc. Whatever is on promotion. Just make sure you get everything for 10/13mm tubing. For pump, I use genuine Xylem D5. They're hyper reliable. You can find them under a ton of names. The easiest tell-tale is made in EU/Hungary. I run them at 100% all the time, no pwm. I have a mish-mash of radiators, all bought used, but from the big brands like EK and alphacool. The older lines are very cheap because they don't look "cool" like the new ones. I've gotten several 360mm radiators for €25-30 a piece. The front radiator in that rig is a 480mm alphacool Monsta, 60 mm thick, and it cost me like €60 shipped, instead of the 200+ it costs new.

For coolant, I just use distilled and de-ionized water with a few drops Povidone-iodine as a biocide. Dirt cheap, very effective, and no risk of it clogging anything. My 3090 rig has been running with this for over a year. Zero issues. PVC tubing will always "ooze" water over time. I need to top the reservoir of that rig once a year or so.

The hardest part isn't making the loop water tight, that's pretty easy with PVC tubing and a smidge of vaseline/petroleum jelly on the o-rings of the blocks after cleaning. It's getting all the air out. That can take 2 hours on a complex loop, where you need to tilt and turn the rig around all axis and directions.

To test for leaks, I just hook the pump to another PSU (shorting the two pins to turn it on) and let the pump run on the loop for 24 hours. This trick is also great to get all the air out without risking damage to the system, since nothing else is on, and the PSU is outside the case. If the level in the reservoir hasn't gone down after 24 hours, it's good to go.

Yes, it's considerably more work to put together than air, but I'd argue the benefits are worth it. First, everything runs cooler and quieter. Second, if you choose your blocks carefully, you can achieve crazy densities without using any risers. Third, speaking of risers, those can bring their own headaches and work. Just look at that pic, eight GPUs on a single board, all with no risers in sight. And did I mention how compact and quiet those things can be?