This case has six external 5 ¼” bays and one of them comes with an adapter for installing a 3 ½” device, which can be a floppy disk drive, a memory card reader or a hard disk drive (the adapter has all the necessary holes). These bays use screwless mechanisms that work very well.

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Figure 18: Disk drive bays.

ATCS 840 comes with six bays for hard disk drives. These bays are small drawers that don’t need any screw or tool for the hard drive installation. They feature little shock absorbers to prevent the noise generated by the hard disk drives from propagating to the chassis and thus being amplified.

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Figure 19: One of the drawers for hard disk drives.

Since you can use the adapter that comes with the case to install a hard disk drive on any 5 ¼” bay you can have up to seven hard disk drives with this case, if you don’t have an external 3 ½” device, of course.