Thanks a million to the senior posters here who replied, yeap the PCI adaptors are cables, I am trying to find a picture of the interior of the 2U.  But it is something like

http://www.amazon.com/Chenbro-Rackmount-RM21600-Supply-Chassis/dp/B005ITOPWW

Power supply is normally quite high at least 750W to accomodate the Raid 5 etc.