HP Compaq dx2100 ST Hardware Reference Manual page 46

Hardware Upgrades
2-36
3. Align the rear guide screws with the rear J-slots on the drive cage
and press down on the rear of the drive 1, then slide the drive
back until it locks into place 2.
Installing a Drive into the 3.5-inch Drive Bay (Hard Drive shown)
4. Connect the power and data cables to the rear of the drive. If
installing a second hard drive, connect the other end of the data
cable to the white system board connector labeled P61 SATA 1.
5. Replace the optical drive.
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