I have just encountered this one as well.
Windows 7 Pro SP1 x64 , so it doesn't have nothing to do with Windows 8.
Samsung 850 Pro SSD / Seagate 1 and 2TB SATA HD's.
X99 UD4 Rev 1.0 BIOS F11 and F12 , it will not enter BIOS if any SSD's or HD's are attached. aThe work around of shifting the controllers to RAID from AHCI is not acceptable to me , Gigabyte need to address this directly and correctly.
I have a development/test system using the same board which is on an earlier BIOS ( F5 ), and it does not display the behaviour, so it is something that has been introduced in the later BIOS's.
An interesting point is that I had managed to do a final configuration of the BIOS after flashing the latest official F11 BIOS , with all HD's attached, but since that initial set up I have not been able to enter BIOS with SSD/HD's attached.
V.C