Installing 870m on Clevo P151EM

[Lament]

Bought an 870m (MXM) to upgrade from the 660m in my Clevo P151EM.

Obviously as it's a GPU upgrade I'll need to modify the appropriate inf from the latest Nvidia drivers.

 

I tried following the guide here, but Windows crashes/freezes when I reboot (after installing the drivers, driver signature check disabled) for a few seconds, and then disabling the 870m with code 43.

To fix this I used J95's instructions for Balamut, to no effect (with these instructions the installer doesn't detect the 870m).

 

As the machine is a Clevo I need to edit 'nvaci.inf', which doesn't include the device/hardware IDs for my GPU (which is a good sign, I guess).

I used the following in '[NVIDIA_Devices.NTamd64.10.0...14310]':

 

%NVIDIA_DEV.1199.5105.1558% = Section086, PCI\VEN_10DE&DEV_1D10&SUBSYS_51051558

In '[Strings]':

 

NVIDIA_DEV.1199.5105.1558 = "NVIDIA GeForce GTX 870m"

...which matches up to my GPU (screenshot attached)

 

The Nvidia installer doesn't detect my GPU with that, I've had some success messing-about with inserting the GPU into the various infs, all end with the same code 43 error.

 

 

Am I doing something wrong here, or perhaps something that I'm completely overlooking?
Using Windows 10 x64.