Using large Dell U2412M monitor here, with CentOS7. It is really slow to boot up, each time it would hang after the following messages for a very long time, with no logs, then it would continue to boot up fine:
[ OK ] Reached target Initrd Default Target.
Welcome to CentOS Linux 7 (Core)!
This does not occur for other Dell monitor like DELL P190S.
Any ideas?