Building a Custom Workstation

Testing The Power Supply Unit

3 min readJul 11, 2020

After planning and getting the components needed, now it’s time to check if my existing power supply unit (PSU, that was purchased and used 10 years ago, transported in a luggage via flight and then was put into storage 5 years ago) still works. You can see previous story on procuring the components,

The PSU to be Reused

The PSU that will be reused for this build is the Cooler Master Real Power 550W, 80% bronze efficiency. Not the best but it suits the need of this build. You can find a 15+ year old review at

This PSU is used to power Intel 2600k (stock speed, no OC) processor and AMD 6850 graphic card flawlessly in the past.

PSU Tester

With new shiny components and a 10+ year old power supply, definitely you don’t want a potentially broken PSU to break your components. So with a 5 USD + power supply tester I’m going to test if the PSU works.

Power Supply Tester

A power supply unit supplies power to all the components in a system unit (the cuboid thingy where you press a button to switch on your computer) . From the Central Processing Unit, Graphic Processing Unit, Random Access Memory, peripherals etc. Many of these components use either 12, 5 or and 3.3 volts. So the tester is capable of testing all the possible voltages that a PSU can supply.

The tester has multiple connectors that you can use to test the PSU. 24 pin (to the motherboard), Molex (4 pin for older harddisk), Sata (current harddisk), 8 pin (older motherboard I believe) and 6 pin (graphic card). Newer GPU uses 8 pin power connector but it’s different than the 8 pin (EPS) motherboard connector mentioned before. Though the GPU 8 connector is not present on the tester, I guess it’s possible to find it on a newer tester.

Testing the PSU

Lights light up when there’s current flow

All you have to do is connect the respective connectors to the tester to test. If there’s current, the L.E.D will light up indicating which volt railing is working. In the case above, my PSU, the -5 isn’t lighting up. I was wondering at first if the PSU has some sort of defect but upon checking online it’s typical for PSU with 24 pin cable to not have -5v.

Power Requirement of The System

As the chip die size is shrinking (GPU and CPU alike) more and more, it becomes more energy efficient and require less energy to power itself, This means, if you have an older PSU like me you can reuse it in future builds with more performant configurations.

Well next, the assembly.


Someone who bricked a motherboard after flashing the wrong rom because of trying to OC an intel celeron from 400mhz to beyond 600mhz in 7th grade.