I mainly use this PC for gaming and school work.
The only real issues that I had was a problem with the RAM seating correctly. Motherboard would throw RAM error post codes. Reseated the DIMMs a couple times and everything was good.
I also ran into an issue with AMD overdrive and MSI Afterburner not playing nice together. Ended up booting into black screens after attempting to OC the GPU. To make things even more annoying, I had enabled fast boot in the BIOS, so I couldn't even boot in to safe mode since it would skip loading the keyboard drivers during POST.
Luckily, the Gigabyte mobo has a clear CMOS switch on it that made reverting my bios settings very easy, and after that, I was able to boot in to safe mode and uninstall both pieces of software and reinstall the AMD drivers again. Everything has been smooth since then. I decided to forego OCing the GPU after that, as the r9 390 really doesn't have much room for overclocking since it's basically already an overclocked 290 with some extra vram.
Card absolute destroys everything I've ran on it at 1080p though. I really need to pick up a QHD monitor and see how it performs there.
Getting a very nice 4.6ghz overclock on the processor. Very happy with the mobo as well as the 6600k.