After further investigation, I believe this is simply a hardware incompatibility issue with the UEFI.
I have three USB devices connected: a MS sidewinder mouse, MS keyboard, and HP printer. The mouse has had some weird behavior in legacy mode when it does decide to work. So I suspect that might not be completely compatible.
But my sansa clip with 16gb microsd (shows as two hdd's in UEFI) seems to create the "b4" no post problem nearly every time.
At the very least, changing legacy usb to "UEFI only" seems to fix it, while still giving me access to BIOS.
Unless someone else can think of something?