Asus x750LB hdd caddy not recognised in BIOS

I have 1TB Samsung hdd as primary (SATA0) and DVD as secondary (SATA2). I have purchased 9.5mm hdd caddy (supports 2.5 SSD or HDD with SATA I-III) and placed 1TB Samsung hdd instead optical drive..SSD disk (z400s) is inserted as primary.
BIOS recognises SSD Z400s normally, but 1TB HDD drive in caddy is not recognised. Not even visible in disk management. Has anybody had similar problems with HDD caddy on Asus X750?

 

I'm not sure you were able to get this resolved already but if not, in disk management check to make sure the drive isn't showing up "unallocated". If it is, simply right click over the unallocated volume, click new volume, click through the options, and assign your drive to an open drive letter.

If it's not showing up try re-seating your drive to make sure your connections is secure. You may also want to see if it's showing up in the BIOS.

 

This is still unreslved. I have tried to re-seat hdd drive and caddy, but its not showing up in BIOS.
Hdd isnt showing up in disk management as "unallocated". This is hdd caddy http://www.digitus.info/en/products...er-accessories/notebook-accessories/da-71108/
Might be that this caddy isnt compatible with Asus x750LB?

 

Nah, not unless they'd purposely block hdds. But that is pretty unlikely; check the bios menus for options related to SATA. Could also use 'reset to defaults' to make sure the port is re-initialized.

There's a small chance the caddy was DOA, of course. Might try it in a different system to make sure; it will also fit 12.5mm systems provided the interface is also slim SATA. Just pad the difference in height with a piece of cardboard or so.