at hiveos, ver 0.7a4 crashed after 3-4h working. rx580 and 570.
I have 0.7a4 working on 12 570 for 5 days without issues.
6 days on 8 x vega64 without issues.
Could you please share your clock speeds and voltages and driver for vegas? I try running the normal Monero underclocks/voltages, get one card that hangs. Run stock settings, whole rig locks up eventually. Have 64Gb of virtual memory, checked the connects, can only speculate issue with either driver/clock speeds.