Rant: Internal or External?

This is one of a series of mini-rants by your faithful correspondent, John Morrison. These are part of a series focusing on issues in the SFF niche. All content is entirely opinion of John, not of SmallFormFactor.net, and should not be taken as fact.

Ahh, the age old SFF conundrum. Do I fit all of the power supply inside the case, or split the perceived volume up and have a power brick under my desk? Is that cheating? Do I include the brick in the final volume of my case? If I do, do I include the volume of my peripherals too? The desk? The room? The house!?! (Sucks if you live in a massive apartment building!)

There is no universally accepted solution here, and the topic is raised over and over again in threads all over the SFF world. Such discussions repeatedly get heated, but if you’re looking for a solution to it in this rant, you’ll be sorely disappointed. As much as this will most likely just add fuel to the flames, it is my opinion. I like to rant, so here goes!

In my opinion, a power brick is just a lump or bump on the power cable. It’s not a way of cheating volume calculations! If you move your system, including cables, you will find it as bulky as you would have had the PSU been inside the case. What you should be considering when designing a chassis, or a building your next PC, is not how big it is in purely metric terms, but what solution works best for you.


An external brick may help you achieve a silent, or near silent, system, or an uber-small form factor. It removes a heat source from your system – always a positive with the density of the systems that we use. It reduces the total volume of the case, meaning you could get your high end desktop hardware in an even smaller box – that sounds ideal to me. What isn’t ideal, though, is the power limits of such a setup, with power bricks greater than 100w quickly becoming very expensive.

SilverStone SX550

An internal power supply reduces clutter, can assist with cooling (the original philosophy behind the ATX standard was using the PSU as an exhaust fan). It also means one less thing in the rats nest underneath your desk.

All in all, this is just my opinion. My personal preference is that an external power brick is definitely acceptable, and doesn’t count towards pure system volume metrics.

What does and does not work for you will vary greatly, and really, the best place to get advise on your use case, is our forum.

Join the discussion here.