I've been struggling quite a bit with this board, and the Intel 750 PCIe drive. If I load optimized defaults in BIOS, the drive is detected in BIOS every time with the Samsung drive. Then I boot into Windows and reboot and I load my OC profile, everything is usually good.
...until I go to BIOS to change anything and save. On the next boot the drive is not detected, only Samsung 960 PRO is. It looks like I need to load optimized default, save, boot into Windows, reboot into BIOS, do changes, save the profile -> BAM drive might not be detected anymore. So then I go to step 1 and get the drive detected again. Sometimes the drive is detected by the boot order is incorrect so the Samsung drive is first - usually if CSM is disabled. However changing this, the BIOS tells me I have not done any actual changes?
Running the latest firmware in the Intel 750 but I cannot detect what is causing the issue. Might be some compatibility issue? I have tried with and without XMP and it looks like enabling/disabling fast boot does nothing. Clues? I might now just try installing Windows on the 960 PRO only and get another drive to DIMM.2 as additional storage.
I don't have high hopes on ASUS fixing this in case this is any bug in the BIOS. They had so much issues with the boards being DOA and it's already discontinued.
W-3175X Asus Dominus Extreme newest BIOS 6x8 GB Corsair Domionator Platinum DDR4-3200 CL16-18-18-36-2T kit (originally 8x8 GB from my X299 build) Palit RTX 2080TI with Galax 380W BIOS Intel 750 NVMe PCIe drive 1.2 TB - Windows installed on this in UEFI mode DIMM.2 with Samsung 960 PRO 1 TB Corsair AX1500i WC on CPU and GPU.
Main: i9-10980XE - Rampage VI Extreme Encore - 64 GB G.Skill Trident Z Royal 3600 CL16 - Strix RTX 3090 - Phanteks Enthoo Primo - Corsair AX1500i - Samsung 960 PRO 1 TB + Intel 600P 1TB - Water cooling HTPC: i7-6950X - X99-M WS - 32 GB G.Skill RipjawsV DDR4-2400 - GTX1050TI - Bitfenix Pandora - Corsair AX860 - Intel 750 400 GB + Samsung 1 TB 850 EVO All around: i9-7980XE - Rampage VI Extreme - 64 GB G.Skill 4000 CL18-19-19-39 - Strix RTX3090 - Phanteks P500A - Samsung 960 EVO 512 GB - Water cooling