I have your answers for this issue, though your question was 3 years ago.
I built my PC 4 years ago (2011), and the problem only happened today. After I opened up case, use CLRCMOS cap to short Pin2-3 for 5 sec (please disconnect power cord for at least 15 sec first), I was able to get back to BIOS/UEFI normally. Then I started fine-tuned the settings one by one for several times, I realized "Legacy USB3.0 support" (under USB Configuration) remains 'disable' would solve this issue.
Now I have my DDR-1333 Kingston 8Gb Dual Channel set, S.M.A.R.T HDD enabled, AHCI support for both SATA2(320Gb HDD) and SATA3(Plextor M6s 128G SSD) enabled. Win7x64 runs perfectly.
Disable splash screen would lead you to "Version 2.0.xxxxx Copyright 20xx American Megatrends, Inc." in the upper left hand corner, and "B4" in the lower right, and just stall there, and I can't be bothered waiting for 15min/30min.
I haven't checked my BIOS version, but I haven't flashed my BIOS since 2011. But it works perfectly now. So I guess I won't flash yet unless it's a must for now. Flashing to new BIOS could lead to other new issues, and I chose to stick to the old one since it's working fine for 4 years.
ASMedia is the chip for USB3.0 and SATA3-addon for this motherboard, I guess this Chip is not working properly after 4 years... but USB3.0 usb drive works fine in Windows environment. And I guess it should work fine with USB2.0 port while installing win7 with my USB3.0 drive. I'll try and report back in 15min time.
If you wanna discuss this further, you may write to my email cos I won't come back this forum after tomorrow. dualmonkey@gmail.com