I connected two OCZ Vertex 4 SSDs using a Molex 4-pin Y-adapter to two SATA power connectors. I have checked the voltages on the Y-adapter and it has 5V where it should be, 12V where it should be and ground where it should be. There's no 3.3V supplied on the SATA plugs; those pins are open-circuit.
I noticed shortly after I powered the system up with the SSDs plugged in, the typical smell, though faint, of smoked electronics. The drives didn't show up. They are both definitely dead now, and wanting to avoid this again, wondering if these have any requirements that make them incompatible with the Molex power adapter cable.
... then I can see what looks like a 5V TVS diode at location D1 near the 5V SATA pins. If I'm right, and if the drive has sustained an overvoltage, then D1 will be shorted. Otherwise, if D1 exists only for reverse polarity protection, then there will be damage elsewhere.
The molex 4 pin power connectors have bevelled corners on two edges so as not to be inserted backwards, but it's not impossible to aggressively push an adapter in backwards. It possibly could be wire backwares, or possibly the Y adapter is wired incorrectly.
Here are images of the standard molex 4 pin power connector.
The Pin 1 yellow wire is always 12v. The Pin4 red wire is 5v. There is no orange 3.3v wire on this connector, and isn't needed for SATA disks.
Check to see if your PSU molex connector is wired this way.
Also, most newer power supply units have SATA power cables, which you could use directly, or attach a male to Y double female SATA power adapter. They will usually have 3.3v supplied to 3 of the 15 pins, but it isn't used by the disk.
Thanks for the responses. I'm not really planning on taking the drives apart because I plan on sending them back. I've done many system builds and I'm completely aware of the way the molex connectors are keyed. I always check the keying to make sure I'm plugging it in the right way. My experience has been that if it doesn't begin inserting easily, I know I have it backwards. The more common issue is that one of the pins will hang up and you have to wiggle it around or come at it from an angle to get all pins to insert without getting stuck.
The power supply is a Corsair TX750 which has eight SATA power connectors. I temporarily need ten connectors while I transfer data off some older drives, so I used a molex to two SATA power plugs with the two SSDs. I've checked the voltages on the Y-connector plugged in to the same power supply with a VOM and what I see is pins 1 - 3 are open, 7 - 9 have +5V, 13 - 15 have +12V and the rest have ground. This matches the pin-out diagrams I have seen for SATA power connectors.
It seems extremely unlikely that I got anything connected incorrectly because I know better than forcing it and everything is keyed, but it also seems unlikely that both drives would fail like this when connected properly. So I'm stuck with a conundrum.
I'll be sending the drives back for replacement, but I wonder what they will find on inspection, and is it possible these units have an internal defect that would cause this?
I plan on plugging the replacements in to the native SATA power connectors on the power supply in an attempt to avoid the problem again, but it will mean I need to plug two other HDDs in using the Y-connector, and since I have no explanation for what happened, I feel uneasy about doing that.
Anyway, thanks for your help. I just wanted to check if there are any known issues with using molex to SATA power adapter cables with SSDs.
ISTM that there is a problem with your PSU. A typical failure is swollen or leaky capacitors. AIUI, this can cause overshoot problems at switch-on, but the voltages may settle down soon afterwards, so you won't see this on your multimeter.
That said, the Corsair TX750 seems to be well designed ...
AISI, there is not much you can discern without an invasive post mortem examination.
Sounds like the molex to sata power adapters may have been built incorrectly, and there's a reversed wire. The only way to tell would be to get a multimeter and check the continuity through the adapter to make sure the +5, +12, and Gnd pins are wired through correctly. If something was wired incorrectly, and the TVSS/RP diode in the drive wasn't strong enough to force the PSU to shutdown, the drives are definitely smoked. I'd definitely check those adapters before putting more drives in harms way.