When you start a miner, one card shows 511 degrees!
Lord, I do not know what to do (
Card RX480 Sapphire
It's not possible for your card to be 511°C. Must be a false reading. Check Radeon Settings temperature reading to determine if the problem is Claymore, AMD or your card.
If the card shows 511 c degree, that mean the card crashed. You need to reduce the frequency.
99 times out of 100 511C means a PSU/RISER problem look at the connectors at the PSU
PSU/RISER PROBLEM LIKELY--
I agree with Klassje. It is likely that a riser is bad. Old, skinny-version risers get really hot and sometimes melt with dual-mining, and even new risers go bad. It is interesting to note that if the problem occurs, the "511C" figure is common. I have had the same readout; the card was good but the riser was bad.
I would stop the rig and change risers before mining again. --scryptr