1.8" PATA
UATA 5000...
ZIF cable interface
I had a SanDisk SDU5B-032G-102501 SSD UATA 5000 1.8" 32G Solid State Hard Drive in one of my C5's.
It does have a FULL Mini PCIE slot..A Mini PCIE SSD drive works nice as a 2nd storage drive.
current drive

SanDisk SDU5B ssd drive I had in one.
