Well, I got this Secondhand server of the config in the image. I want to buy a UPS for it but have any clue about them. It has to back up the server monitor and a printer for at least 4hr, I understand that UPS are not meant for the sustained load so what other way is there to get this amount of backup.
Power supply specs: Supermicro 560W/600W 1U Multi-Output Power Supply (PWS-563-1H).