You're going to love this...
It is very probable that issues with panicky GT 330M's isn't actually a problem with the GPU as many have thought.
According to [https://forums.macrumors.com/threads/gpu-kernel-panic-in-mid-2010-whats-the-best-fix.1890097/#post-23125275|this amazing thread on MacRumors]:
''"Apple made the same mistake they made with the 820-2610 and 820-2330 where they ran out of space on the motherboard for C7771 so they made it a tantalum one. This is not suitable for a rail that is always on, as C7771 is for an S5 rail - so it dies. Voltage fluctuates, and eventually the machine stops turning on. On the 820-2850, that same 330uf tantalum capacitor re-appears on the framebuffer power supply for the GPU and the VRAM.''''
One possible fix is to replace the dodgy cap with a regular type, however in the mentioned thread you'll find a soft workaround, which involves patching the Info.plist of AppleGraphicsPowerManagement.kext.
And the best bit....
I got my GPU Back!!