your Question not clear , u sing 2 HDD okay.
1. check which one is boot disk(which one is having operating system that is boot disk)
for ex: HDD1 : loaded operating system.
HDD2 : not Loaded Operating system.
2. go to CMOS settings .
set HDD1 Is First Boot Disk okay. HDD2 is Second Boot Disk...etc(HDD,CS/DVD....)
change Jumper Settings for HDD(See jumper settings in back side of the HDD)