There are a few things you need to know before you decide if you can use an old PSU in your new computer. first, make sure your computer is compatible with the PSU. If it isn’t, you may have to buy a new one. second, be sure to check the voltage and wattage of the PSU. Many computers now come with built-in voltage regulators that allow you to change the wattage of your PSU without having to remove it. If your computer doesn’t have this feature, you’ll need to buy a power supply that has this capability. Finally, be sure to make sure that the power cord is long enough for your new computer and the old PSU.
Yes, You Can Reuse a PSU in a New Build
While PSU design and manufacturing have improved incrementally over the years, the fundamental standards haven’t changed much. A 2010-era PSU design will power an ATX motherboard and peripherals just like a 2020-era on would.
So when it comes to updating an older PC or building a brand new one, the consideration is rarely “is this PSU high tech enough for my build?”
The focus is usually exclusively on updating the CPU, motherboard, memory, GPU, and the flashy bits—who isn’t excited to jump from old hard drive tech to a new NVMe drive? There are PC parts you can reuse, however, and the PSU is one of them.
But, Consider These Things Before Reusing a PSU
Just because you can reuse your PSU, doesn’t mean you should default to reusing your old PSU simply because it powers up.
Here are some important things to consider before using your old PSU in your new build.
Is the Wattage Rating High Enough?
Your PSU might have been powerful enough for your previous build, but the demands of your new build could exceed what your old PSU can deliver.
That 650W PSU might have been perfect (overkill, even) for a build with a GTX 1080 GPU, for instance, but won’t cut it for the significantly increased power demands a new gaming PC built for an RTX 4080 will have.
To better understand how to account for increased power demands, calculating headroom, and other considerations, check out this article about purchasing a new PSU when upgrading your GPU.
Does It Have All the Connections You Need?
Your older PSU might have the same primary connectors as a newer PSU, such as the standard 24-pin Molex power connector, but the number of peripheral cables and their pinout patterns has increased and changed over time.
If your old PSU only has a 6+2 PCIe cable (8 pins across two connectors) for the GPU and you need an 8+6 PCIe cable (12 pins across two connectors), you’re out of luck and you need to upgrade.
Typically not having enough connectors corresponds to not having enough wattage, the previous issue we mentioned, so you’ll likely resolve both issues simultaneously.
Speaking of connections, this is a great time to remind everybody that modular PSU cables are not interchangeable, and if you’re moving PSUs around, you need to move the PSU cables with them.
Is the PSU Still Within Warranty?
Finally, is the PSU still within the original manufacturer warranty? If you’re reusing an old PSU for a low-cost build with old parts, this might not be as much of a consideration.
Throwing together a franken-build so your niece can play Minecraft probably doesn’t necessitate an upgraded or brand-new PSU.
But if you’re building a new PC with new (and likely high-end) parts, it’s worth considering the age and warranty status of the PSU. Throwing a ten-year-old mid-tier PSU that’s seven years past its warranty date into a new PC is not a great plan.
On the other hand, putting a five-year-old high-quality PSU that still has years left on its ten-year warranty into a new build isn’t a big deal. As long as it meets your wattage and connection needs, that PSU still has plenty of life left in it.
Regardless of how new or old the PSU is, we highly recommend taking a few minutes to test your PSU before reusing it. Testing a PSU is simple and it’s so much easier to deal with problems on the test bench than to try to isolate irregular and frustrating issues caused by a failing PSU.
