Hello! I have experienced a very strange issue with a new rMBP that has confounded Apple techs and geniuses. Apple has given me a replacement machine and replaced the logic board, and each time, within a few days, it's bricked. Apple has offered no advice except "we'll fix it the next time it happens." I turn to you––hopefully more interested in solving this issue than Apple––for advice. Many thanks for any input. Here is what happened: Death #1 On Jan. 2, I purchased a new late-2013 rMBP. About 10 days later, the machine mysteriously restarted in the middle of the night and would not boot. All I got was a black screen; no software or BIOS loaded. The screen was illuminated and the Apple logo lit up, but I couldn't boot to an external drive or reset the PRAM. The power light on the MagSafe connector indicated that the SMC reset was working, however. I took the machine to the Apple Store and a genius confirmed the above. He sent the machine to a repair depot, which recommended replacing the logic board and display. At this point, the Apple Store simply gave me a brand new machine. Death #2 I used the new machine for about a week and the same thing happened again––the machine restarted and would not boot. Black screen, no BIOS, etc. I took the machine to the Apple Store and the geniuses were stumped. I asked what could cause this to happen and was told that it would be shipped off to techs at a repair depot who would investigate. There was no investigation. They replaced the logic board and display and returned the computer to me without any advice Death #3 Two days after receiving the repaired computer, the computer bites the dust again. An Apple genius offered that a USB device may be creating a power surge and that I should stop using all USB devices with the computer until I find out which device is defective. But this seemed an amateurish diagnosis at best: Can USB devices really fry a logic board? Aren't USB connections limited in the power they can transmit? Possible causes Power adapter: After the second frying, I volunteered a piece of information that was dismissed by the geniuses: I am using a 2006-era 85W MagSafe power supply with a MagSafe 2 adapter. While Apple says this is safe, two Apple techs advised me that this could be responsible for power issues damaging the logic board. (They told me this after the third death.) External devices Can an external USB device destroy a motherboard? I have been using all of the external devices connected to the destroyed rMBPs with previous-generation MBPs for years with no issues whatsoever. [CLARIFICATION: The previous MBP was a mid-2012 model with USB 3 ports; these peripherals have all played nice with USB 3 ports for about 20 months.] The peripherals include: - 3 powered USB hubs - Multiple hard drives - DVD writer - DAC - Printer - Scanner Software On both machines that died, I had migrated from the same backup via Migration Assistant. Is it conceivable that a software issue could prevent a machine from booting as I have described? Thanks again for any advice!