First of all - a UPS is an uninterruptable power supply. You're talking about a PSU - power supply unit. A UPS is an external box that basically keeps powering your computer if it loses power due to a power outage, etc. A PSU is the thing inside your computer that plugs into the wall and powers all the components.
Run this for starters, it'll tell you the general state of your computer and what you can to to fix it: