Hi UnclWish,
I already explain even without warm up my rig with 8 GPU RX 580 8GB on first print hash rate it already reach max on all GPU.
Windows 10 Build 1709
AMD Driver 18.6.1
2 thread multi_hash 944
Maybe in your case because you have latest Windows 10 and latest AMD Driver.
Maybe you're right. I have 1803 Windows 10 and 18.11.2 drivers... Still playing with GPU voltages to check...
Or maybe your cards have good samsung memory... Or maybe your memory straps better than my...
What memory type and clocks/voltages you use? What memory straps?
JCE, can drivers affect that way?