Today, I bought 2 more Sapphire RX580 with Hynix memory, they are both run about 22mh/s, and I tune/mod bios,they are still 22mh/s.
try a different motherboard, I have an older motherboard that does the same thing on my rx400 series while flashing/overclocking them (22MH/s), but when moved to my mining motherboards they run fine
Yes that is a great idea. I tried that on mobo 2 of "BIOSTAR TB250-BTC PRO"(6pcie) and "Gigabyte xxx"(my game computer ), they all do 22mh/s, but other GPU on these 3 mobo is 24mh/s means can up to 31mh/s.
Maybe it is not the mobo issue?
Any other advices?Thx.