Having trouble resolving an issue with my GPU constantly crashing while gaming. I had a R9 290x and in December, all my monitors randomly went dark while playing PUBG. It ended up being that it killed the GPU and it could no longer POST. For the next few weeks I was able to play very res games using my integrated graphics. I then received a brand new GPU as the 290x had a lifetime warranty, so I just got a new R9 390x a week ago. Same problem, instantly crashed out when I tried to join a PUBG lobby.
I started playing some less-intensive games like SMITE, Portal 2, LoL, etc.. and these actually did okay. SMITE crashed once, but usually I could game for several hours fine. I then tried Civ 6, which was good for an hour then crashed. By crash, all 3 monitors go dead but I still hear sound in my headphones.
Up till now I have had a stock cooler and thought maybe my CPU was overheating (was about 75-80C in SMITE, and 85-95C in Civ 6), installed the new cooler 2 days ago and got SMITE down to 65-68C, but the issue still occurs, and now it is occurring on SMITE often. I also have noticed that if I have remove my side case and stick a large fan nearby, this seems to help with some of the crashing, however, my GPU and CPU temps seem fine, if not lower, so I am not sure what else would/could be heating up?
My current setup is:
CPU: INTEL I7 4790K 4.0G 8M R
Intel Core i7-4790K Devil's Canyon Quad-Core 4.0 GHz LGA 1150 88W BX80646I74790K Desktop Processor I...
With brand new Corsair H75 cooler.
RAM: Ripjaws X Series 16GB (2 x 8GB) 240-Pin DD
Motherboard: GIGABYTE GA-Z97X-SLI
GIGABYTE GA-Z97X-SLI LGA 1150 Intel Z97 HDMI SATA 6Gb/s USB 3.0 ATX Intel Motherboard - Newegg.com
PSU: EVGA 850W 110-B2
GPU: R9 390x-8256 (Driver: tried both the latest V17 and V18 one)
Monitors
- (1x): https://www.amazon.com/ASUS-PB278Q-2560x1440-DisplayPort-Monitor/dp/B009C3M7H0/ref=sr_1_1?ie=UTF8&qi...
- NEW (2x): https://www.amazon.com/gp/product/B01CX26WPY/ref=od_aui_detailpages01?ie=UTF8&psc=1
Things I have tried so far:
- New GPU (from the RMA)
- New Cooler (2 days ago)
- Resetting all components multiple times.
- Uninstalled and reinstalled all drivers 2-3x now.
- Test 1 RAM stick at a time to see if it boots fine.
- Tested memtest86 on both sticks with no issues.
- Double checked all windows updates.
- Monitored and logged temperatures to make sure they looked fine.
- GPU is usually 70c's (fine for this card from what I read)
- CPU hasn't passed 70c now with the new cooler on it.
- Checked event logs for any weird errors before GPU crashes, nothing really there.
- Tested PSU voltage with Multi-meter, everything looks good there too.
- Checked for any specific driver updates for CPU and GPU.
The only new new change to my setup over the past ~4 years (when I got all of my hardware) was that a week before the first crash happened in December (that killed my original GPU), I went from 1 to 3 monitors. I had a nice 2560x1440 which is still in the middle, and then I bought two 1920x1080 curved monitors to go on each of its sides. I presume 3 monitors is fine for a r9 390x though? I only game on the main monitor and use the other two for spotify/discord/web/etc.. Everything was running great for a week (high intensity games and such) until it randomly crashed one night and killed the GPU (no POST).
Anyways, I believe I fixed all the potential problems, and tried all the other things I can think of. I just am not sure what to test or try next.. I thought maybe it was PSU but the voltages looked good, and I am not sure how to test my motherboard or CPU to ensure they are "good". Could there be any issue with my outlet not giving enough power with 2 more monitors? Could something still be overheating despite the lower/better temps?
Just pulling my hair out at this point trying to figure out what could be going wrong. 
Please let me know any information you want/need, I will get it to you ASAP (unless I am at work, then I will do it first thing when I am home).
Thank you!
Hi @Pokester.
YOU ARE A LIFE SAVER 
I have been having so many issues with my OC'd Vega 64, with it crashing during stress-tests and benchmarks, I almost lost hope and thought my card was a dud. It wouldn't crash in games, unless I put the graphics to maximum, but even UserBenchmark and Furmark 720p preset would immediately crash it.
I put my Wattman profile to manual, as you suggested, and increased the Power Limit to the Maximum 50% and restarted and Furmark 720p didn't crash the system as it previously did.
EDIT: Although FurMark 720p now works, the 1080p preset still crashes the system. I've now read that because I have Vega 64, I should use two different power cables., rather than a daisy chained one, even though I have an HX1200i from Corsair.
EDIT 2: According to my UserBenchmarks, I have actually previously benchmarked this card using my old PSU and Driver 18.9.1, so either my new, much better PSU is funky, or the latest drivers are causing something weird to happen.
Which psu, 850 or 450 ?, have you been troubleshooting with just one monitor connected ?
What OS, build No./vers. ?
