Hello,
What are your settings for the RX580 8G? Core Speed/Mem Speed/Voltage? What do you have your -h set at? Are you running SMOS?
I'm wondering if you are able to get it stable for longer than 24hrs. I can usually get my RX580 8G rigs stable for 5-8 hrs but then it will reset so I end up getting 3-4 resets in a day. When I was mining ETH with the same rig, it would be stable for 24hr+. Right now my settings are 1200/2000/1000mV with a -h of 1600 running SMOS. I am also running RX570 4G rigs and they are a little more stable at 1-2 resets a day. Not sure why the higher memory cards are having issues. Settings for the 4G cards are 1200/1750/1000mV with a -h of 850 running SMOS.
Both of my rigs are using 11 GPUs, 8G of RAM, z270 chipset.
Cheers,