The PSU supplies power to the 5.25” PST which can be mounted in a spare bay. Three LEDs on the front show you that voltage is being supplied along the different rails. Using proprietary connectors, you can then run power to nearby components straight from the PST or take it on down to the Mini PST and your SATA drives will plug straight into the PST itself.
http://www.hexus.net/content/reviews...lld19JRD0xMjQw