NEED HELP/Upgrade : MSI GT60-0NC GTX 670m issues. Possible to upgrade? gtx 770m?

Hello friends! I need so advice!

Laptop : MSI GT60-0NC, i7-3610QM, GTX-670m, 8GB ram.

Backstory: Got the laptop, loved it, worked great. Sudden framedrops followed by persistent blue screen after around 1 year use. DRIVER_IRQL_NOT_LESS_OR_EQUAL (nvlddmkm.sys)

Thought it was a driver issue - unninstalled, reinstalled, disabled, re-enabled, updated etc etc, no luck. fully disabled the GPU and continued with the iGPU. Few months past decided to get to the bottom of the problem. Removed the GPU, no visible thermal dmg, reinstalled - same BSOD.
Ran GPU-Z, card is recognised but load is 0%

2 Theories:
1) GPU is completely fried, if it is can i replace it with a 770m/780m? will i need to get a GT60-20D heatsink (the one with the copper pipe across from gpu to cpu heatsink) or will the stock heatsink do?

2) Optimus is being , which is possible since i had to completely format all my drives and reinstall windows (upgraded to 8.1 at the same time) and maybe i missed something? i read something about flashing the vbios but my google search just got me even more confused than before. The card is recognised but not being loaded.


If anyone has any suggestions on how to fix it (yes i tried msi nvidia drivers- got a driver verification BSOD)
or
If anyone can advise me on what is the max power GPU i should be looking for to replace the 670m with, do i need a new heatsink too? (the dye on the 670m is rectangular wheras on the 770m it is square), or can i ghetto fix the heatsink to the gpu? Also - should i (or can i) slot an i7-4xxx series Haswell based CPU into my system or are there compatibility issues?

Thank you in advance
<3

 

bump <3 <3 <3 im trying to find somewhere in EU to buy the gt60 2od heatsink, but so far no luck

 

Probably is a bad card. I don't think the 770M likes the older optimus systems, any 6 series card (MX varients and 680M will need a new heatsink) or the 780M with appropriate system bios will work.