Yes.  Plus we know it definitely isn't a Windows problem as it rebooted during diagnostics.  I've also been thru PSU problems myself.  When they get into that random reboot habit, they eventually die. I remember you once suspected the RAM.  If it were bad, the PC wouldn't boot at all.  I think it fell into the category of not enough power from PSU on all the rails.  Also:  PSU Testers on Amazon 
I've been recently having problems with my T3610 where it will randomly turn off and the power button will flash orange. I leave this workstation on all the time so I can't say what might be happening prior to the crash, but there are no errors in Windows event viewer. Sometimes, I can just unplug it, wait a minute and plug it back in and it will come back on. More recently, I've had to remove the RAM and Processor to get it to come back to life. I originally suspected the power supply, but after the most recent crash, it no longer registers the memory in DIMM8 and DIMM4 (i.e., in the BIOS, it acknowledges the DIMM is present and it sets the memory to 4-channel, but it detects 0MB rather than 8MB), so now I'm wondering if the motherboard is dying. Does anyone have any ideas on how I might isolate the problem?
T3610 Blinking Orange Power Button