Ever since I built my system in May 2012, I have never seen anything on either of my monitors showing the POST and memory check. Only after I hear the POST beep do I see something on the display; and that is the Windows 8 loading screen).
Is there a setting in the P9X79 Pro's BIOS to enable and disable the display of the POST stats? If not, then why am I not seeing anything until the POST is successful and Windows starts loading? I do have the UEFI/BIOS logo shut off, but would that kill the rest of the info displayed as well?
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I don't often get too deep into the specific BIOS/UEFI settings, but seems like a simple enough test to me. Try enabling the logo setting and see if you get any video output.
For the most part, the whole point of UEFI is to just do the bare minimum needed to initialize the hardware, then get out of the way for the OS. It's not intended to be as heavy/full featured as the old BIOS.
You should see POST information at the beginning of the POST process, but it probably is just POSTing too fast for your monitor to come on. The Boot Logo adds a second or two to the POST process, so you are basically just slowing down the process to the point where the monitor (or possibly video card) can catch up.
As long as you can still enter the BIOS, I wouldn't worry about it and would keep the BIOS Logo disabled. No reason to add to your POST times if you don't need to IMO.