I've had poor results with overclocking the 4 GB Sapphire Nitro+ 480s. I believe they have slower RAM than the 8 GB version though. Is it stock 2000 Mhz on the 8 GB version ?
I don't think you will be able to overclock to 2100 - maybe try stock setting and see if it is more stable.
I would try a slower GPU clock setting and lower GPU and RAM voltage - I think I had mine running at:
-cclock 1150 -mclock 1850 -mvddc 950 -cvddc 950
Try yours at -mclock 2000 and work from there.
Yes stock BIOS and stock setting run stable.
Stock setting :
CClock 1340 mclock 2000 cvddc 1150 an mvddc 1000
That runs stable. As soon as I higher Mem to 2100 it crashes over a couple of hours mining. If I can not overclock, I really should be able to reduce the power. Otherwise this was a bad investment. I have 4 cards now but I already ordered 12 more. But I ordered ASRock h81 pro btc motherboard as well, maybe that will be better?