More than likely, the board is showing that screen ,but boots faster than monitor, so it is not shown. ASUS BIOSes that added Windows8 support VASTLY improved boot times, when they boot right.
You can fix possibly by adding to the delay that the screen is shown, on this page(although there should be many more options with Windows8 BIOS). This screenshot is not form your board, but it should work in a similar fashion.
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