My PC will not boot from the hdd and goes straight to BIOS, reporting that a boot drive could not be found. Neither will it boot from disk drives using various Windows, DOS boot disks. It did boot to a USB Win 10 recovery drive but recovery could not solve the problem, presumably because boot drive could not be found. I replaced the power unit months ago but it has worked fine until now. After boot to BIOS, I see all drives listed, but that's it. Motherboard is an Asus H97-Plus, CPU is Intel i3. I have tried multiple solutions found online - switching/replacing SATA cables, removing all components but hdd and GPU. Also switched in a second GPU to another PCI-E slot, all to no avail. Help.