Hello Guys,
our cluster runs till 2014 on supermicro board.
It is not unusual that still mainboards with mga graphics cards are delivered.
So I have then adjusted the mga driver from centos 6 - the specification file - , to be build on CentOS 7. Since then this runs on the headnode without failures.
Maybe you should provide this via epel. The source can be found here:
http://centos.cms4all.org/repo/7/drivers/SRPM/xorg-x11-drv-mga-1.6.3-11.el7....
This is the latest from Centos 6.9.
Sincerely
Andy