That is rather odd and should definitely not be happening. Can you tell us a bit more about your setup?
Which OS version are you using? What version drivers are you running? Which version of the miner are you running?
Do the stats still display when you press 's' ? How do you know if it's just one GPU that crashes?
8 x Vega56 MSI Air (original bios, no software timing mods)
Win10 LTSB, 18.6.1 drivers, latest 0.5.7 miner
's' shows only one string as in attached image.
one gpu is just a guess. first it began rebooting with "GPU 6: detected DEAD" in log for the last two days. than began hanging like screened. if I reboot in manually, it works for serveral minutes, after that same behaviour again. rig power drops to ~370W. I realize that code is multi-thread, but it seems like it waits for something before giving them next jobs.
txt log shows the same thing, nothing special.
upd now I've disabled gpu6 using "-d" key - same result some time later
upd2 now another rig shows almost same picture. it has 8 Vega64 liquid. same OS, drivers and miner, same pool. maybe there's something connected to difficulty growth?