I have a Windows 2008 Standard R2 server with a redundant power supply (2 modules, hot swap). The customer asked me to monitor the PSU because they can't hear it beeping. It's connected to an APC SmartUPS 1500 without SNMP card. The server runs an ASUS Z8NA-D6 mainboard. Until I'm putting my hands on the physical machine (and remove all case panels) I'll not be aware of the PSU brand and model.
I heard about using SMBus and asked the customer to check if there is a cable coming out from the PSU. Unfortunately there is no SMBus cable.