Hi @Klem,
did you could help applepiefly out with his/her "error 43" problem??
I have the totally same error on my stock GTX 780m in my Clevo P157SM to what the card came with and hope to fix instead of replacing it.
The error occour after a failure in Adobe Photoshop CC with blue screen. Since then the card never reactivates, but it's still recognized in BIOS, Windows and everywhere else, but without stats in GPU-Z as shown from applepiefly. But when I deinstall the nvidia display driver back to Standard VGA Driver, then GPU-Z is able to load all stats from the card o.O
I also modded the inf-files of the nvidia 430.64 display driver, to support my GTX 780m furthermore, because it's told this version has a "error 43" fix for first time with it. But still no luck!
Please help me too!