download cuda driver from NVIDIA website.http://www.nvidia.com/Download/index.aspx?lang=en-us
yum install kernel-devel kernel-headers gcc make(if needed)
edit /boot/grub2/grub.cfg, add  rdblacklist=nouveau at the end of vmlinuz-3.xx.........
reboot
init 3
./cuda.......run

yum -y update
yum -y groupinstall “GNOME Desktop” “Development Tools”
yum -y install kernel-devel
Edit /etc/default/grub. Add “rd.driver.blacklist=nouveau nouveau.modeset=0″ to “GRUB_CMDLINE_LINUX”
grub2-mkconfig -o /boot/grub2/grub.cfg
List available kernels: awk -F\’ ‘$1==”menuentry ” {print $2}’ /etc/grub2.cfg
Use grub2-set-default to set the updated kernel to the default. The kernels are enumerated starting at 0
Reboot
Download the appropriate Nvidia driver for your card
Switch from graphical to text mode: systemctl isolate multi-user.target
Run the Nvidia driver installer
Remove the nouveau driver: yum remove xorg-x11-drv-nouveau
Backup old the old initramfs: mv /boot/initramfs-$(uname -r).img /boot/initramfs-$(uname -r)-nouveau.img
Create new initramfs: dracut /boot/initramfs-$(uname -r).img $(uname -r)
Reboot

To install ELRepo for RHEL-7, SL-7 or CentOS-7:
rpm -Uvh http://www.elrepo.org/elrepo-release-7.0-2.el7.elrepo.noarch.rpm
To install Repoforge
rpm -Uvh http://pkgs.repoforge.org/rpmforge-release/rpmforge-release-0.5.3-1.el7.rf.x86_64.rpm

NEXT is the procedure on CentOS 6

Installing Nvidia Driver on CentOS 6 PDF Print
Written by Sargis Dallakyan
20 Comments
This post explains how to install NVIDIA proprietary drivers on CentOS 6. By default, CentOS 6 comes with nouveau drivers, which for 3D (OpenGL) rendering, is order of magnitude slower that NVIDIA's proprietary drivers. For instance, I had glxgear running at round 400 frames per second (FPS) before installing NVIDIA proprietary drivers and at around 1000 FPS after. So it pays to add this extra step to your CentOS 6 installation. Before we start, make sure you have all required packages installed:
yum groupinstall "Development Tools"
yum install kernel-devel kernel-headers dkms
The last package (dkms) is needed so that we don't have to reinstall NVIDIA drivers after each kernel updates. Now we are ready to download NVIDIA proprietary drivers - http://www.nvidia.com/Download/index.aspx
To find out your Video Card model number, click Main Menu → System Settings → Display or run:
lspci | grep VGA
I then run /sbin/init 3 and then chmod +x NVIDIA-Linux-x86-290.10.run followed by ./NVIDIA-Linux-x86-290.10.run. However, this gave me:
"ERROR: The Nouveau kernel driver is currently in use by your system. This driver is incompatible with the NVIDIA driver, and must be disabled before proceeding. Please consult the NVIDIA driver README and your Linux distribution's documentation for details on how to correctly disable the Nouveau kernel driver."
After trying many different options I have found a solution described at http://www.linuxquestions.org/questions/ubuntu-63/nouveau-kernel-driver-825432.
So I added the following line to /etc/modprobe.d/blacklist.conf file
blacklist nouveau
and then did:
$ mv /boot/initramfs-$(uname -r).img /boot/initramfs-$(uname -r).img.bak
$ dracut -v /boot/initramfs-$(uname -r).img $(uname -r)
Reboot and run ./NVIDIA-Linux-x86-290.10.run to finish installing NVIDIA driver.
Another difference, between CentOS 6 and earlier versions of CentoOS is that system-config-packages (Add/remove applications) is now called gpk-application. You need to run yum install gnome-packagekit if gpk-application is not installed in your system. Also, if you are planning to do OpenGL development run (source: www.centos.org - Forums - CentOS 6 - Software Support - Help me ..):
yum install mesa-libGL-devel mesa-libGLU-devel