I would first update the drivers.
If your system still is not stable, (keeps BSOD), i would test your memory again.
According to the memtest tutorial:
Let it run until at least 8 passes are completed, or errors are found (whichever comes first). The longer you run it, the better.Seven passes will take several hours, depending on your amount of RAM. It is advised to leave it running overnight.
1) Bios V206-207-208 - G750JWAS207.zip - I have 207 - should I update to 208? If so, how do I install it? The file in the zip is ____.207 for 207 or ___.208 for 208
2) BIOS-Utility - Windows BIOS Flash Utility V2.24.0 - do I need this?
Check the readme file to see if they apply to the problems that you are having. Please be advised that flashing the BIOS is a very unforgiving process - and one mistake can physically damage your motherboard.
208 = Fix that CPU and GPU will be throttled immediately when change to DC mode.
Do you have problems with cpu/gpu throttling.
3) Chipset - Intel INF Update Driver V9.4.0.1022 - do I need this?
Yes, Always update to the latest chipset version
4) ATK - ATKACPI driver and hot-key related utilities V1.0.0031 - do I need this?
Advice: if you use it or it is installed,always update to the latest version
5) AUDIO - Realtek Audio Driver V6.0.1.7095 - I had V6.0.1.6954 - DONE
6) VGA - nVidia Graphics Driver V9.18.13.3788 - I had 9.18.13.3165 - DONE
7) LAN - Qualcomm Atheros LAN Driver V2.1.0.21 - already have this version - NO CHANGE
8) Card Reader - Genesys Multi-Card Reader Driver V4.3.0.7 - not sure what this does or whether I need it?
Yes, update
9) TouchPad - Elantech Touchpad driver V11.5.12.1 - I had 11.5.9.1 - DONE
10) Utilities -
(a) Power4Gear Hybrid Utility V3.0.8 - what is this? do I need it?
(b) ASUS Splendid Video Enhancement Technology V2.01.0021 - don't see this listed under video - what is it? do I need it?
(c) ASUS USB Charger Plus V2.1.5 - I don't see this either - do I need it?
(d) Keyboard Device Filter Utility V1.0.0.5 - already have this version - NO CHANGE
(e) ASUS Live Update Utility V3.2.6 - don't see it - do I need it?
Advice: if you use it or it is installed,always update to the latest version
11) Wireless - many listed but I do not see any of them in Device Manager - should I be looking elsewhere?
You have Broadcom 802.11ac Network Adapter, update to the latest version
12) BlueTooth
(a) Intel BT Driver V3.1.1309.0390 - I do not see this installed, all I see if 2 Microsoft ones, neither listed here
(b) Broadcom BT driver V12.0.0.7900 and 7800 - 7800 (2013.12.17) is dated later than 7900 (2013.10.14)! I have 12.0.0.7820, dated 2013.08.30 - based on this which (if any) new one should I install?
The latest
13) Others -
(a) Intel Mgmt Engine Interface V9.5.14.1724 - do I need this?
(b) Intel Rapid Storage Technology driver V12.8.0.1016 - do I need this?
Yes, update