Freeze on awake

After a few good days it occurred again. WhoCrashed did not find a minidump to work with. However I went through the event list again and while I still couldn't see an entry from the time of the failed awakening, I noticed the following error in the System event list:

Code:

The previous system shutdown at 9:48:01 PM on ‎2/‎25/‎2016 was unexpected.

The timestamp matches the time I sent the PC to sleep last night. Maybe something goes sideways while going to sleep? Or it could be that it froze so fast that it couldn't update some data and after the reset it still thinks it was reset last night...

March, April and the first half of May was somewhat bearable, I only got a freeze maybe once a week. However in the past two-three weeks it's bad once again, I have a 50-50 chance to see a proper wake up.

But why I'm posting is that I've just observed something interesting: the machine was in sleep mode, I woke it up, desktop showed but everything was frozen, HDD led was constantly on. I swore and hit the reset button. For several seconds nothing happened (not unusual) then the pc restarted. However this time instead of a fresh windows start I got my suspended session back! I saw the same desktop with the same apps open as the first time but now everything was working.

I really hope this is not a one off event, this waking bug is really getting on my nerves...

Hmm interesting... how would I check if it's a PSU issue? My PSU is about 30% oversized, I prepared the HW for overclocking which I never bothered with.
I render quite often, calculate lighting for a game engine but never had an issue. However I probably should log voltage values with some monitoring app to get an idea about their stability. And do some memory testing. Yeah it's just so weird and unheard of that it could very well be some HW trouble...