Hi,
Been trying to figure out why my Asus Z270-WS likes to shut itself off and on 3-4 times before it starts up and posts to loading windows. Did a lot of trial and error and narrowed it down to how the bios allocates resources such that when setting a PCIEX4 slot to X2 operation the motherboard will have difficulty directly starting up from a cold unpowered state. Setting the PCIEX4 slot to X2 operation in bios frees up the front panel USB 3.1 controller which is otherwise disabled when the PCIEX4 slot is set to X4 operation which also fixes the issue. To make things even weirder when the USB3.1 controller is disabled either by PCIEX4 X4 setting or just disabling USB 3.1 Controller the Device Manager will get hung up on a mystery usb device it fails to enumerate or recognize. Disabling Fast Boot in Windows and via Bios has solved this issue. Anyhow was wondering if anyone else has encountered this issue and what their thoughts are on this?
Note: Also have NVME Raid 0 enabled on this board along with SATA Raid and have devices on the U2_1 port and in the PCIEX4 slot occupied with a SSD.
Thank you
This report best passed on to Asus, but it may not help them put out a fixed version, but I would let them know your testing and findings anyway so at least you give them chance to improve the BIOS
You should put board title in topic title, so other users with same board could chime in too 
Issue may be related to ME FW settings and functions, swapping lane functionality etc.
Thank you for your response and I have to say I agree with that assessment. I have been in contact with Asus and they deny there being a bios issue and want me to rma the motherboard. Currently on latest ME firmware for that board and have disabled the front usb 3.1 port so board no longer triple posts anymore. Rather have all my ports functional. Thanks.