Small computers for MacCHESS

A mini-ITX computer with full-size keyboard.

In the last few years, I have tried to combat the tendency of computers to get bigger, hotter and louder by choosing machines that meet performance requirements and yet are smaller, cooler and quieter.

For the MacCHESS crystal centering application, it is necessary to place a computer in the hutch to service the FireWire digital video cameras. Thus, small size is an important consideration. I chose to assemble mini-ITX computers in Casetronic Travla C-138 cases, which are 20 x 20 x 10.8 cm. The first set of these centering servers used Commell LV-671 motherboards with Intel Pentium M CPUs, 2.5" laptop hard drives and 90 W power supplies. The innards were replaced in 2006-2007 with either Commell LV-677 or MSI MS-7265 motherboards and Intel Core 2 Duo (Merom) CPUs. The cases were designed for lower power VIA CPUs, so it was necessary to modify them with an additional 60 mm fan for cooling. You can spot these machines in the hutches if you look around a bit.

In the photo below, you can see how these mini-ITX boxes (five of them) stack up against one of the larger extended-ATX full tower cases in the lab.

These machines do not need optical drives for routine use, so I saved space by not including a DVD drive. Software installation was performed using an external USB DVD drive.

For the latest update to beamline data processing workstations, I chose micro-ATX motherboards with Antec NSK3300 cases (35.6 x 35 x 20 cm). Micro-ATX boards have all the features of full-sizede ATX motherboards, but with fewer PCI expansion slots. Since the introduction of FireWire and USB, internal PCI expansion is no longer as important at it once was.

One weak point of the NSK3300 case is limited hard drive space. This is acceptable for MacCHESS use since our beamline data is stored on RAID subsystems and shared over our gigabit network. Despite its small size, the NSK3300 case has a 120mm fan in the back. Due to their large radius, 120mm fans can maintain an adequate flow rate while spinning at a lower RPM, thus reducing noise while maintaining adequate cooling. These workstations currently feature a dual core AMD X2 5200+ EE CPU rated at 65 W power consumption.

For a while I tried out some Soltek small form factor computers. These "shoebox" size machines have a socket A Athlon processor. I was not overly impressed with the air flow through the cases, provided by a single blower geometry fan. These are still serving as desktop machines for some MacCHESS staff.

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