Do SSD's die when plugged in PSU with different SATA Cable?

Me and my roommate both plugged an SSD into an Corsair 650W PSU using a SATA Cable that was shipped with EVGA's 500W Bronze PSU. It did not boot once, everytime we try to start the PC the PSU (doesnt matter which) instantly shuts down, refusing to do anything. Neither SSD now works with the old PSU's where they have been plugged in the last year.

Did we toast both? Is there anyway to rescue the SSD's themself?

Sadly, yes that is very likely to happen... Corsair and EVGA both use the same 6-pin connector, and I don't believe they key it differently to prevent cross usage.

Corsair's modular 6-pin "Perhipheral" pinout (on the PSU):

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EVGA's modular 6-pin "Perhipheral" pinout (on the PSU):

_(source)

As you connected the EVGA cable between a Corsair PSU and SSD, you will have connected things like this:

Arguably, this is the "safer" way to have done it... with 5v and 3.3v feeding the 12v and 5v supplies respectively - the SSD may be okay. If you had used a Corsair cable with an EVGA PSU, you'd be in a worse situation for sure...

As you'll notice, the 5v and 0v lines are shorted through the cable or SSD's 0v path, which explains why the PSU is turning off immediately (the short circuit protection is kicking in).

However: If the SSD uses the 3.3v supply, it will very likely be dead... but many drives don't use this.

The 12v rail typically comes up before the others (especially if the others are derived from it) meaning that the 3.3v supply to the SSD would have been at 12v for some time (death is almost certain)... at least until the 5v rail was established and the short circuit protection kicked in.

My advice? Always use the correct cables, and try the SSDs with a known-good power supply... they may well be fine.