My understanding is for legacy bios motherboards, devices have to present an OpROM to be bootable whereas UEFI utilizes drivers. The Samsung 850 Pro reportedly is one of the last ssd drives to include both driver for UEFI and an OpROM making it legacy compatible. Somewhere it was mentioned the PM953 is something like an OEM version of the 850 Pro. But the literature on PM953 is pretty much non-existent. Just wondering if anyone has tried so I don't have to waste time and money testing.I think that would be a factor of the motherboard and not the actual drive itself.