Apple has released an updated version of its Apple Server Diagnostics that tests for hardware issues in servers running Mac OS X Server 10.6. Like past versions, this one runs a customizable set of tests for identifying issues with server components such as the boot ROM, Ethernet controller, fan, hard drive, memory, power supply, processor, sensor, USB ports, and video controller.
The update is compatible with Snow Leopard Server on the Xserve (Early 2009), Xserve (Early 2008), and Mac mini (Early 2009), and is available via Software Update or the Apple Support Downloads page. Apple also notes you can run Apple Server Diagnostics in Extensible Firmware Interface (EFI), in Mac OS X, or in Mac OS X Server. (Free, 20.2 MB)