I have a MSI GT72 2QD (Haswell) and I tried a HP power supply with the same specifications as the original (230W?). Same result.
After I flashed the newest EC firmware and vBios from MSI I was able to play for 45 minutes instead of 5.
After that my notebooks shuts down again. No bluescreen or something else, just goes off.
Temperature should be no problem. I changed to liquid metal after I faced the problem and it reached not more than 65°.
No dust or anything.
I also unplugged the battery and tried it only with the power supply.
I think its my vRam which is fucked up whyever.
My last hope is a modded vBios maybe 2 variants I could try.