Hi Ken,
I put the drive in another machine and did the SSD Toolbox Full Diagnostics and it Passed.
But I couldn't do a Secure Erase because I'm on Win 8. I tried to boot Linux from a USB-drive but neither the mouse nor keyboard was working, so I couldn't do a Secure Erase.
I will try again in some different way...
While I was investigating the machine I tried to boot it with just the motherboard plugged in, but it failed. When I pressed the power button on the case, the fans spun up for a second then it turned off again. I suspect some sort of No Load Protection on the PSU being cause. So I plugged in 4 WD Red drives to the backplane of the case to give it some load, but it still wouldn't start.
The PSU, a Silverstone SFX ST45SF-G 450W is completely modular and specified to be able to run with 0 amps load. It have 2 x 6-pin connectors for SATA and Molex cables. The Molex one is connected to the backplane, feeding power to the storage drives, the SATA one is connected to the Intel SSD. It was impossible to get the system to power up without anything plugged in to the SATA power cable, wich doesn't make the PSU very modular! I have emailed Silverstone to ask them if this is expected behavior or if I should RMA the PSU.
Will keep you updated.
EDIT: Just got words back from Silverstone Support. They think I got a faulty PSU and they want me to RMA it. Will get back when I get the new PSU.