Second time in last couple months usually when not in use, I'm getting a multi color herringbone pattern on my two monitors GPU. temps in normal range. GPU is RX 480 also been having random crashes. Could this be graphics card issue? I just updated to latest radeon drivers. Rest of the the setup is a Ryzen 1700 on Asrock Micro ATX
Does this occur all the time even when booting up or just when on the Windows desktop?
Try stress testing your GPU card and see if the artifacts occurs. I personally like using OCCT, a free stand alone program to stress test my CPU, GPU, & PSU hardware or you might want to try Furmark to check if it is a heating or stability issue.
Overheating seems to be the main reason for artifacts or a GPU card going bad. Run OCCT GPU Test and see if you get artifacts or any GPU errors. If you don't, then run OCCT PSU Test for the same issue. Both times keep an eye on Temperatures and PSU outputs for anything abnormal.
If you get artifacts during any of the stress testing and your GPU temperatures and voltages are normal, then try downgrading the AMD Driver that worked without the artifacts. If that doesn't help then I would suggest you open a Warranty Ticket (if still under warranty) or Support ticket with the manufacturer of the GPU card to see what they recommend.
Since I posted it hasn't happened once, never when booting up only when not in use, hasn't happened once when playing GTA or anything else GPU intensive but I will do a stress test to be sure, temps should be normal as they never go past 52 degrees C when playing games like GTA I usually use Afterburner to monitor temps at the moment with normal non gaming use it's at a steady 41c GPU fans running at the moment. It's an old card out of warranty if need be I will need to replace it, but we'll see what the tests reveal.
I've done all the required tests, the issue hasn't happened since last I posted, however, last night when I tried to go into Hibernate it happened again the pattern is very different from the other one, take a look at this picture and tell me if you can figure out what could be causing this?
sounds like a possible BIOS fault, check to see if there is an update