Windows detects hard drive BUT Bios does not

Hi There,

Unusual issue. Have been setting up a backup PC, so have crammed it full of harddrives - 2 x 3tb, 1 x 2tb and 1 x 500GB for the OS.

However it just can't detect SATA Disk 1 in Bios even though I can access it in Windows. Therefore I get a warning everytime on load up and now it is also showing that Disk 1 is unallocated in Computer Management even though it appears as G:/ in explorer and I can access files. 

This is causing a few problems with broken links, syncing and updates, so if anyone has any suggestions how to fix this let me know!

Details

Running Windows 7

HDD replaced CD drive.

Graphics card is slightly faulty but don't think this should effect anything.

The Hard drives are different brands and sizes (but never had any issue with this before)