Use the following guidelines when choosing a case:
If you are migrating an existing motherboard, buy a case to fit that motherboard. If you are building a new system, buy a case that accepts full ATX motherboards, even if you’re installing a Mini-ATX or microATX motherboard. A full-ATX case allows upgrading later to a full-ATX motherboard, and provides more working space even if the system will never have anything larger than a microATX motherboard installed.
Using a small motherboard (or one with poorly placed ATA connectors) in a full- or mid-tower case may require drive cables longer than the PATA maximum of 18 inches. Using ATA cables longer than 18 inches may corrupt data, particularly with Ultra-ATA hard drives. If an 18-inch cable is too short to reach a hard drive mounted in one of the top bays, you may be able to mount the drive in an internal bay that permits using the 18-inch cable. If not, consider substituting a SATA hard drive, which can use a 39-inch cable. Optical drives operate at lower data rates than Ultra-DMA hard drives, so there is less chance that data will be corrupted by a longer cable. Although we cannot recommend using P-ATA cables longer than 18 inches because they do not comply with the ATA specification, we have often used 24-inch cables for optical drives without experiencing data integrity problems.
Choose a case that leaves at least one or two bays—ideally 5.25-inch external bays—free ...