Kanrail

See the problem i have is they are using the newly added hot spot temp. Use the edge temp like every other gpu released to date, and stop worrying over a new sensor AMD added. It wont throttle until 110c on that hot spot temp, ive had my 5700 xt for a week now and the hot spot has never gone over 85, and ive been really cranking the settings and or frame rate. Keep the stock card, mines a stock blower and i love it. No thermal issues at all. I came off an R9 390 which would game at 85 to 94 edge temp, i cant even fathom how spicy the hot spot was (because it wasnt reported on older gen gpus) Why worry over a temp thats reached by every single gpu out their, but just not reported to the user due to lack of a sensor. Its silly.

The card runs hot, as long as you aren't playing in like a 35c room, you really don't need to worry. refunding for a better after market cooler will be way cheaper than going custom water-cooling. The heat isn't a driver issue, so that hasn't changed anything, all they could change with that is more aggressive fan curves or less clock boosting.
 
So think of it this way, Water cooling is fun, and can look cool. Really expensive.
You aren't losing any performance if you just leave it as is, however it might be louder than you like.
Refund to swap to a 3rd party cooled card will be your most cost effective option aside from just leaving it as-is.