Hi -
It can be a challenge to get GPU drivers working on linux - here are some instructions that might help, based on this document about how to start from scratch on a virtual machine. The are for debian but centos should be similar I guess.
Execute the following and take note of the BusID
sudo nvidia-xconfig --query-gpu-info
Open the X11 configuration file
sudo vim /etc/X11/xorg.conf
and insert the following BusID line using the BusID value you retrieved earlier into this Section:
Section "Device"
Identifier "Device0"
Driver "nvidia"
VendorName "NVIDIA Corporation"
BusID "PCI:0:4:0"
EndSection
or if /etc/X11/xorg.conf does not exist, create a file in /usr/share/X11/xorg.conf.d/xorg.conf with the contents listed above.