800 is around the limit you can go on the S9 with 880. I mean you can go higher but the HW error rate will quickly climb to far and outweigh it. The errors rate looks good at about 1 error rate a minute after running it for some time it should steady out or drop too. If you ran 890 I bet the 800mhz would have close to no HW errors but would probably trip the 1600w psu and shut it down. Keep it at 880 for 1600w psu