SAme thing on my multi-gpu rigs have 2 of them one is 8 nvidia 1070's+ 4 rx580's the other is 8 nvidia 2070's and 5 rx580's both seem to crash randomly... both using the asrock htc+ mining mb, oddly enough I have had a straight nvidia 1070 rig with 8 mining fine that never stops, it seems something to do with mixed rig is causing the crash. One important note though from phoneixminer 4.5c and before I had ZERO problems both these rigs would run fine for weeks. I even lowered my clocks and tried all that seems random sometimes they run for hours and then crash to a desktop, not noticing much freezing though with 4.9b. And no its not a power issue both have dual 1300 watt psu's and only use 1300-1400 watts... Any help appreciated.