Hi guys,
thank you for the suggestions!
I tried first disabling the WiFi card in device manager, but no results. Physically removing it from the NUC also did not improve the situation (I thought perhaps there was some kind of interference with the unifying receiver...). Kept the WiFi card out for a few hours, but I never saw any BSODs.
After moving away the unifying receiver (connected over USB extender cable), the results improved somewhat (meaning there was no more crashes & reboots, however the result was Windows freezing with corrupted display). This has also happened many times in the BIOS (different kind of screen corruption & freezing, but still corruption). Also tried inserting the SO-DIMM to the other slot, no improvements. Also tried with wired mouse & keyboard, but Windows kept crashing.
@ SFrost007: my screen looked similar to yours.
I have then reinstalled Windows 7 ultimate x64 from scratch and installed only the Rapid Storage driver, GE LAN driver, WiFi & BT driver and USB3 driver. This time I am also using wired mouse and wired keyboard from the beginning (no Logitech software installed on the NUC yet).
Now it is running for 7+ hours, browsing various Internet pages and so far it's rock stable (earlier, it was never possible to run for so long). I will keep it running like this for a while longer and then install the remaining video and audio driver and Logitech software, so it is going to take time (have to go to work tomorrow...). Because I have seen the same thing happening when I booted the live Linux Mint 16 off the USB stick, that makes me think that Logitech software should not be causing freezes & reboots, but let's see).
I kept the power brick approx. 30 cm from the NUC chassis for the whole time.
Thanks again, I will post back my findings in a day or two. Anyway, the suspect list is now narrowed down.
Cheers,
/HarveyV