A guide on how to make the, HP DPS-800GB Rev. A, server power supply run outside of its server enclosure. Be sure to check out the related posts or make a search here on the site for other server power supply hacks.
A simple bridge between pin 31 and 34 is required and it is important to NOT drill holes through the GND and +12VDC output pads, this will risk short-circuiting the output as its a 4-layer PCB.
These power supply units can be connected in series to get 24VDC or 36VDC. More than 3 units in series will have higher chances of power supply failures. The internal ground connections on the secondary side has to be removed, to avoid short-circuit through the mains ground or between the metal enclosures. To learn how to remove the correct ground wire and put these power supplies in series, read this article on the subject: Putting server power supplies in series for 36VDC.