ok this is a strange one , i got a third AR version of this chipset its the prime Z270-AR

the other two are working fine with 8 cards , 7 on pcie and one on m2 adapter , this board

worked fine wth 4g decoding and 5 cards, two days later tried to add 3 more cards, now it crashes right away after bios screen, uninstalled drivers wit uud, i see all 8 cards , crashes again when trying to update driver.

tried to rol back to my original 5 card build removing the extra 3 cards same crash when installing drivers

same crap happens when i reinstall win 10 ... flakey board?