Convert An Old PC ATX Power Supply!

I’ve used many different power supplies over the years to power my lighting projects however very few have lived up to my expectations especially under heavy loads. Many of the so called high current Chinese designs can have suspicious ratings to say the least with some being positively dangerous.
Your precious pixels need worry no more as an old ATX PC power supply with a relatively simple mod can offer a clean reliable high current power source, that will provide many years of service.

I’m not going into the construction side of things as below are some great links that provide all the info you need. The first guide is my favourite that I originally used 13 years ago.

My original guide -

Any questions on modding, please feel free to ask.


Love it! Funny story I tried using a couple old supplies. They were unstable due to the aging of the caps. I took them out of good computers but they sat in my hot Texas garage for 5 years. The voltages were ok till I put a load.

I was bummed cause I saved them for the reason of being a power supply for projects. Oh well I just bought a new power supply didn’t feel
Like repair old ones.

It’s strange that you experienced issues with some old PC supplies. A few of mine are pushing 15 years old and still going strong with some being used daily.
I guess your hot garage may not of helped matters. We don’t have that problem here in the UK… :cold_face:

Depends on the age. A while back, there was a massive QC issue with caps.

I’ve never experienced the Cap problems mentioned although I’m fairly choosy on not using the budget brands often included with cheap PC cases. The 3 supplies in my pic are all 10 to 15 years old so maybe I’ve been lucky.
I’ve found the older ATX supplies are still easily sourced and often obtained free, so no real hardship if I do one day encounter a problem.

I’m using some recycled ATX PSUs too, but take care when using 5V lane only, because some of those PSUs don’t like to give too much 5V power without a load in 12V lane. In addition is good practice to test this under heavy loads, to avoid caps problems like you said.


Yes I have experienced this once on a cheap unbranded supply. I’ve heard of people using a 12v car bulb to create a load however it’s not very energy efficient. What I have experienced more is getting the 12v line actually up to 12v, assuming you are going to use it. More than often the 10 ohm 10w resistor may need further reducing to 8 ohms or less. Most quality supplies I’ve converted can usually achieve at least 11.6v on the 12v rail which is still within the industry 5% tolerance. The 5v rail doesn’t normally drop below 4.8v under load.

A required-load is inefficient. :wink: Not sure if newer supplies don’t monitor load current.