Antec Server Series Atlas w/o PSU Server Chassis with 120mm Rear Fan, 92mm/80mm Fan Mounts, 8 Total Drive Bays, 7 Expansion Slots for Standard ATX, MicroATX and Mini-ITX Eight Drive Bays - Four external 5.25"(with one 5.25" to 3.5" adapter); four internal 3.5"removable HDD trays with rubber grommets to isolate drive vibrations Ease of Use - Removable side panel and front bezel for easy access to drive bays Advanced Cooling System - 1 rear 120mm TriCool 3-speed fan, 2 front mounts for optional 92mm fans, side panel vent with mount for optional 80mm fan Front Ports - Two USB 2.0, one IEEE 1394, Audio in and out ports Technical Features - 7 expansion slots; motherboard compatibility for ATX, MicroATX and Mini-ITX