If you take the time to read the CCSI history on our home page, you will see that the original rack mounted PC was in the 4U form factor. This was principally a result of the adaptation of the then “state of the art” IBM PC AT desk top computer, to a rack mounted configuration. While 4U was the original “standard” for rack-mounted computers, it has become less necessary and consequently less popular as ever higher levels of integration have been offered with successive generations of motherboards, requiring fewer expansion slots to provide necessary functionality. Another factor has been the rapidly increasing capacity of hard drives, currently as much as 4 Terabytes. 4RU, which is 7.0 inches of vertical rack space, allows sufficient room for 7 full sized expansion cards or even up to a 20 slot passive backplane and as many as 24 Hot Swappable 3.5 inch hard drives or even 36 when mounted in front and rear or 48 2.5” drives. CCSI 4U Performance Servers are the right choice for customers who need more expansion slots than a 2U system supports and more hard drive capacity than a 3U system can provide. Another new utilization of 4U server chassis is the Fat Twin which can house either 2, 4 or 8 independent servers in a single 4U chassis. CCSI Performance 4U Servers are available with single AMD or Intel processors; AMD Opteron™ servers, Socket 1155 or Socket 1366 Core™ i7 servers, and dual processor or quad processor, quad core, six core , eight core or twelve core AMD Opteron™ servers and Intel dual-processor Quad-Core, Six-Core, or Eight-Core Intel Xeon™ servers.