Powercolor Red Dragon RX 580 8 GB memory speed drops to 300 as soon as it starts mining.

I am not having a real good run with these Powercolor cards today. As soon as it starts mining, one of my 6 cards memory clock drops to 300 and mining speed drops to zero. Claymores detects that it is stuck and restarts. Most of the time at this point the pc freezes.

I have tried it in the PCIE slot of the motherboard (Asrock Z97 Extreme 4) but no luck.