Already using after burner
None, apparently, lol it's not got a reading for that :SOn the MSI Afterburner tool, what Core Voltage are you using? My Twin Frozr II was set to something like 9.75Mv and my PC would power off when playing games. I changed it to 1v and it's been fine ever since.
Maybe as a test, increase the Mv ever so slightly (if you're on 9.5Mv, change to 9.75Mv). Don't wanna go higher than 1.05v though.
Also you can try increasing the graphics card fan speed as this will be set to auto. You could then play BF4 and see if the problem remains. If so, change the fan back to auto