Hey, as well even though this is fixed in the development branch I was asked by
one of the other nouveau guys to post this for people running older kernels
since it's easier to backport. This is a very dirty hack that disables the last
512 MB of VRAM for the GTX970, however it does technically fix the issue and
let your GPU run. If you can't use Ben Skegg's patch, give this one a try