I added another external HDD bay to my computer and ran out of SATA power plugs. Dang! Grabbed another cable to plug in the PSU and the HDD, turned the computer on and the fan made a tick and that was it. 
WHAAAAT? Man, that can't be... the HDD ran 10 mins earlier.
The problem happened, because I grabbed the wrong SATA power wire for the PSU. Here is a little warning: An Antec PSU has the same SATA power plugs than an EVGA PSU. They will fit each other perfectly, BUT: they are wired backwards!!!
What happens then is that either the Computer stays is STBY and when you press the on button, it only turns on for a split second, or you hear the HDD spin up, doing some scratching, then spin down again. That's it.
On the back of the HDD is a little circuit board. Depending on brand / design you may have to remove it to get at the bad component. The SATA power has three voltages. In my case the plug was wired backwards at the PSU, so 12 volt got on the 5v rail and shorted the TVS diode that goes from 5v to GND very near the plug in. Remove the bad diode and all is well, but it is not protected anymore from power spikes or from another power reversal, wrong voltage, etc. The TVS diode had marking AE which is a 5v TVS diode that works both ways, unlike a regular diode. Replacement was a 1SMA5.0 available at Digi-Key for my Hitachi HDD.
Apperantly I am not the only one and found this at WD website:
https://community.wd.com/t/hdd-tvs-diode-faq/14692
Surly sux, but haven't lost the drive.
WHAAAAT? Man, that can't be... the HDD ran 10 mins earlier.
The problem happened, because I grabbed the wrong SATA power wire for the PSU. Here is a little warning: An Antec PSU has the same SATA power plugs than an EVGA PSU. They will fit each other perfectly, BUT: they are wired backwards!!!
What happens then is that either the Computer stays is STBY and when you press the on button, it only turns on for a split second, or you hear the HDD spin up, doing some scratching, then spin down again. That's it.
On the back of the HDD is a little circuit board. Depending on brand / design you may have to remove it to get at the bad component. The SATA power has three voltages. In my case the plug was wired backwards at the PSU, so 12 volt got on the 5v rail and shorted the TVS diode that goes from 5v to GND very near the plug in. Remove the bad diode and all is well, but it is not protected anymore from power spikes or from another power reversal, wrong voltage, etc. The TVS diode had marking AE which is a 5v TVS diode that works both ways, unlike a regular diode. Replacement was a 1SMA5.0 available at Digi-Key for my Hitachi HDD.
Apperantly I am not the only one and found this at WD website:
https://community.wd.com/t/hdd-tvs-diode-faq/14692
Surly sux, but haven't lost the drive.
2. They're not standardized.
3. Another connector, another failure point.
4. PSU is effectively bigger now that there's something sticking out from the back and something that was really close to fitting no longer does.
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