Kernel panic Mac Pro 5.1 Titan X

Getting kernel panics every morning, not sure whats causing it but all drivers are up to date and running OS 10.10.5

Any help much appreciated.

*** Panic Report ***
panic(cpu 0 caller 0xffffff7f9d2afb54): NVRM[0/5:0:0]: Read Error 0x00000100: CFG 0xffffffff 0xffffffff 0xffffffff, BAR0 0xa4000000 0xffffff8754139000 0x120020a1, D0, P2/4
Backtrace (CPU 0), Frame : Return Address
0xffffff8753d13710 : 0xffffff801c72ad21
0xffffff8753d13790 : 0xffffff7f9d2afb54
0xffffff8753d13850 :...

Kernel panic Mac Pro 5.1 Titan X