AemiliusPaulus

What are your idle temps on it? I just upgraded one of my GT 240M M15x models to the GTX 660M, but despite a careful (and purposely sparse) application of Arctic Silver 5, the GPU still idles at 65C with fans at 2,8000RPM (manual with Hwinfo since the fan control doesn't seem to work automatically). Also, you didn't get the fans to work, did you? I got the Dell 660M, but still no automatic fan control.

Has anyone ever gotten a 780M to work with M15x? I know the 680M worked, so 780M not so different, eh? On the other hand, I've heard of 765M failures...

Amazing that you did this with M15x, but do you have an M18x R1/R2 to try it with? I feel like watercooling that will yield much better returns for the work you put in, lol.

DId you check GPUz to see if it is running at the clocks and frequency that it should be? Maybe your system is throttling it. 240W adapter should be enough. Also, try running games to see how it runs, benchmarks may go wrong, but hard to argue with FPS in games,

What sort of issues? If you install the drivers with modified .inf, it should work, no? I mean, the 765M is Kepler, not much different from 660M and 680M.