I know this sounds a lot like this but I just confirmed that my MBR is fine as well as the SSD drive in question. What happened: I upgraded my be-quiet 700w PSU to the 1000w dark power pro. When I tried booting the system and none of the drives (all SATA) were detected, resulting in the "Boot device failure" error. After that I unplugged all but the boot drive, triple checked that all cables were in fact nice and tight inside their sockets, replaced both e-SATA and power cables ; still with the same outcome. Finally I reconnected my old PSU and sure enough the PC booted without any hassle (except of course for the direful construction that is currently occupying my desk). Does anybody have any advice on how to proceed? Surely, it is possible the PSU is faulty but are there other explanations? Thanks in advance PS. if of any help: Motherboard is GIGABYTE GA-PH67A-UD3-B3 H67 LGA 1155