I am new to mining and I am using some Radeon Saphire 580 8gb nitro+ cards.
I got everything built and flashed the BIOS using a backed up original and then applied Polaris one click.
This boosted by Mh/s to around 28 but I am getting "share rejected " error quite regularly on all my GPU's at random times.
Reading into this it looks like an overclock setting but this is without overclocking, just running Claymore dual miner (I am just mining Ethereum). If I overclock I can get 30 mh/s and it still does the same thing, not really any worse? Ethermine shows I am losing 7% of shares.
I have several friends running the same setup with the same pool and running reliably so must be a setting somewhere. Is there any ideas before I flash bios back to original and see what happens?