SPEC:
ASUS Zenith Extreme TR4
-snip-
[Windows 10]
*Newest drivers
4 cards seems to work (10 min test)
5 cards unstable (crash after few mins)
Maybe this note from the motherboard's specification can explain it:
1. The PCIE_X8/x4_4 slot shares bandwidth with U.2. In 4-Way configuration, if the PCIE_X8/x4_4 is used in x8 mode, U.2 port will be disabled.
Since it only has 4 PCI-e x16 slots, I assume that you've connected a riser to the PCI-e x8 slot.
Mining will surely use it in x8 mode and will disable the U.2 port which is used by your SSD (
you haven't specified if you're using SSD though, do you?).
Non-working 4 Cards with Linux however is weird, that board was designed to work with 4 cards.