Specs from c|net
Original PSU rated at 280 watts.
You need to test your psu voltage output with a digtal multimeter. Analog multimeters are not as accurate, and depending on the circuit being tested, can cause damage if used to check and done improperly.
Standard 12 + volt range tolerance: 11.2 - 12.6 volts Anything outside of this range is out of specs and may result in a system that does not start.
Aging psu's will put out less stable power over time; higher gamer psu's rated at 800 watts when new will put out up to less than half that in two or three years, depending on quality of manufacture and type of use/demands.
A failing or failed psu can cause damage to the motherboard, hard drives, other peripherals, and even cause corruption of some files in the resident operating system.
So, the next task should be to back up all important files on the dead computer using your second computer to copy and transfer your files to two different medias for your backup purposes. You do that by removing the hard drive from the dead computer and connect it to the working one via an USB external drive enclosure.
Good program for checking various hardware parameters on a running system here: http://www.almico.com/speedfan.php Numbers displayed here within the program are very close but not 100% accurate; use a digital multimeter to get an exact number.