One other bit of info I thought about that could be contributing is my horizontal monitor is hooked up to a cheap 4 port HDMI switch (not a true KVM switch, it's HDMI only). This seems to cause the monitor to flicker back and forth during boot / loading the splash page as it looks (to my untrained eye) like it can't decide if the HDMI is hooked up to a monitor or not. Once the login page is displayed though that particular problem is gone until the next boot.
One other bit of info I thought about that could be contributing is my horizontal monitor is hooked up to a cheap 4 port HDMI switch (not a true KVM switch, it's HDMI only). This seems to cause the monitor to flicker back and forth during boot / loading the splash page as it looks (to my untrained eye) like it can't decide if the HDMI is hooked up to a monitor or not. Once the login page is displayed though that particular problem is gone until the next boot.