[phanbuey]

well its either the SSD or the PSU, very unlinkely that it is a faulty motherboard. Here is what I would do:

1. Image the SSD while its up so you dont lose anything.
2. RMA the SSD and the powersupply.

Or

1. Image the ssd.
1.5 Flash to latest Firmware (is problem still happening? if yes go to step 2)
2. see if it happens with another PSU / when using the USB adapter (SSD's can pull enough power from the USB to run), if YES then SSD is dying, if NO then PSU is dying.
3. NO - Replace PSU. YES - Replace SSD.
4. If still happening look at motherboard.

Dying SSDs are known to 'dissapear' like that (it is actually very common - as a quick google search will prove), so brace yourself.

Some have had success by flashing the firmware of the drive. But it is most likely the SSD itself.