Question ASUS ROG GL552JX RAM and SSD upgrade causing random restarts (sometimes with BSOD)

[tidbits]

Need help! I'm almost at my wit's end.
Upgraded a friend's GL552J laptop (the BIOS detects the motherboard as GL552JX).

RAM: From 1x4GB to 2x8GB DDR3L RAM,
SSD: installed an additional SSD in the M.2 slot (Kingston A400 SATA SSD - 240 GB, M.2 form factor).

Although I managed to boot, and even clone the OS over to the SSD and boot from it, I started to encounter random BSODs and sometimes it just shuts down without warning (no BSOD).

Decided to uninstall the SSD, go back to booting from the HDD, and removed 1 stick of memory so it was just 1x8GB RAM (still an upgrade over the original 4GB). The system was a lot more stable, but the shutdowns are still happening without a BSOD and not even when doing anything CPU intensive.
What could the problem be? I've done memory checks (maybe not enough passes?), I've also updated the BIOS.

Any ideas from the forum?

 

[helpstar]

check heat of GPU and CPU

which BSODs are there?

does it happen with and without the charger?

Does it work again with the one 4GB Dimm?

Which RAM did you install? brand and exact model please

Check the contacts/cable/solderjoints of the HDD/SSD between connector and motherboard

 

[tidbits]

It was running a little hot >70C but not always consistently hot when it shutdown.

A couple of BSODs I encountered, again, not consistently were: irql_not_less_or_equal and kernel_security_check_failure

Yes, it happens with and without the charger. I even set active cooling when on battery.

I haven't switched back to the 4GB DIMM, that's my next course of action once I get my hands on the laptop again. But not before I run more memory test passes on the 8GB RAM. (update: it shuts down spontaneously after booting to Windows and i haven't had the chance to even start the memtest)

The upgraded RAM is a couple of Samsung 8GB DDR3L 1.35V PC3L-12800