Greeting all!
I have played the Witcher 3 for months without a single hitch but ever since i have upgraded my PC i get a black screen on startup.

My specs :
GeForce GTX 950
Intel(R)Core(TM) i7-4790k CPU @ 4.00GHz
32 GB RAM
1920 x 1089 , 60GHz

I run it through GOG client and have tried numerous fixes such as updating drivers, disabling Geforce etc but none seem to work.

Any help is much appreciated
Kind Regards

And yet the one obvious thing to try you don't mention: verify/repair your game through Galaxy.