Sounds like a power issue. Check your risers power distribution. Preferably one riser on a single sata cable but we know it`s not always possible. Never power more than two risers on single sata cable.
My calculations your rig pulls about 800watts, that is high for only a 1000watt psu.
Disconnect one card and see how it goes.
Yeah this is a good point.
He could disconnect 1 card or drop them all to 115 watts. Yeah his hash will drop with way but 5 cards at 115 watts is 575+75 other = 650-675
I kind of think he has too high of a ram setting and cards are getting tired of the setting. My 3060tis are set a lot lower.