I have 3 Asus motherboards, both Maximus codes can do this, both which are lesser boards.
This is a basic thing, I wouldn't doubt this capability. If this doesn't work there is something wrong with your board.
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I only doubted because a few x399 boards I'm looking at make it a point to specify (os bootable from nvme).
Which gives the impression that other boards that don't mention this, don't have this feature.