Forcing a specific video mode, Centos 7

At the grub prompt, edit the line for the specific kernel and at the end of the line add:


for 800 x 600 resolution with 24 bit colour.

To make this permanent:
Edit /etc/default/grub and add the video= to the end of GRUB_CMDLINE_LINUX line.

# grub2-mkconfig -o /boot/grub2/grub.cfg

This will force the video mode for current and future kernels