Doctor,
Could you change the id of gpu to match with GPUZ.
my rig has 12 gpu and i'm very confuse, cant find gpu which has low hashrate.
thank you.

Ok, suppose the order is same as in GPU-z. and card 4 has low hashrate. What now ?

I don't really understand why is the order important. You can move mem clock + 1 in OverdriveNtool , press H in SRBminer and see which cards mem clock raised by 1

Now you found which card is it.