I originally intended to build a sub-$1000 PC using ThoughtA's Great AMD Gaming Build as a template. I replaced the case with Fractal Design Design C Mini mainly for the aesthetics and reviews.
Then a friend sold me a pair of his GTX1080s for a pretty decent deal, which threw things off the rails. I got an SLI-capable motherboard instead along with a beefier power supply, both of which upped the price a bit. I don't really need SLI, but I wanted to give it a shot.
The extra fan upgrades were completely unnecessary, as the stock Fractal Design Dynamic GP-12 fans that came with the case were more than adequate. I figured with the SLI setup I'd give air cooling a boost. Both the original fans and replacement fans were whisper quiet, where the only sound you'd hear is the movement of air, and even then only at full load.
By far the loudest component on the board are the 3x fans on each GPU. At full load, you can hear the whooshing of air even 10 feet away.
This PC is currently driving an 55" LG OLED B7 display at 4K@60Hz in HDR. The only time SLI shows its worth is when playing The Witcher 3 at that resolution, where it can still manage > 45-fps even on busy scenes. On the other hand, XCom 2 still brings this down to its knees, but that's mostly because it's probably CPU-bound more than GPU-bound. All other games I play in my Steam backlog have 300+ fps which is ridiculous. Maybe one day I'll get to use a more standard monitor, but for now, Steam Big Picture + Xbox One S / PS4 controller + this build is pretty awesome.
If I had to do this all over again, though, I'd stick with ThoughtA's build — significantly cheaper and gets the job done, especially for the kind of games I play.
Most likely in a few weeks time, I'll pull out the second GPU and sell it along with my unused monitor.