I have a weird issue with the 0.33b5 on the CN V8 (XMR).
Both my two RX 570 start running at ~1005 h/s, which is nice.
But after a random time, from 2 minutes to several hours, one of the cards (randomly again) has his hashrate suddenly dropping to ~960 h/s and it stays at this value until the miner is restarted.

If my settings were wrong, such with a too high multi-hash, the hashrate would drop always after the same duration, pretty soon after the miner is started, and not randomly as it happens to both my cards.