The Pis shine primarily in terms of power consumption, under load, a mini PC could cosume 50W, where a Pi (and other ARM boards) will do an absolute maximum of 15W. And if you have multiple devices that run 24/7, that could be a significant saving
Like others have said, the PCs you're looking at might be mini in form factor but specced more traditional desktops. There there are plenty of mini PC options that compete at 15 watts and lower range. One example I use is https://www.amazon.com/Computer-Windows-Dual-Band-Bluetooth-.... This gets you built in 128 GB eMMC, dual display output, more USB 3, about the same overall CPU performance but significantly higher single core scores, an open native SATA slot,
Similarly there are boards even cheaper than this passively cooled, and will pull less than 15 watts under load as measured from the wall while being in a preassembled case.
The best part is it's easier to scale to your needs. E.g. if a single $200 box can get the latest generation CPUs that will absolutely demolish these cheap ARM boards in perf/watt, come with PCIe m.2 drives, support higher RAM limits, and have GPUs that are more on the usable side of things. As a result it can do the work of multiple devices (if you don't need them to be physically separate of course) and will last significantly longer in terms of usability.
Wattage for the whole thing is as mentioned, TDP of just the CPU is 4 to 6 watt (configurable). This particular one has a fan which will kick in if you run it hard for long periods, for truefanless I'd suggest the B1 instead. Or if you go for the splurge you can knock cTDP down and still run circles around the pi in performance.
It'll run anything but if you want to avoid paying the "windows tax" out of principal the best way I've found is to buy one from Ali Express or the like. If you're in the market for the slightly higher end options they also have more varied fabless systems there too. Most of the stuff you find on Amazon is geared towards your average consumer looking for a cheap PC so come with Windows.
I've been using a few mini PCs for things where I needed a headless system, but wanted x86_64 and a little more performance and reliability than a Pi, I settled on N3350 devices like the N4 by TrigKey or the Beelink T4.
Everything I need is supported by Ubuntu server. Excellent little machines.
The trouble there is if you're actually compute bound, the Pi's performance is also a lot worse, and if you're not, you should be comparing the idle power consumption. There are plenty of PCs that idle at under 10W.
PCs also support arbitrary amounts of memory, so you can often avoid needing multiple devices by using virtualization.
Also, if you start piling up PIs because one won't have enough compute power and memory, you are likely to habe a lower electric footprint with a single nuc and virtualization or containers.
Just have to pay attention and be picky while shopping for the mini pc. Yes most of them are way over 15W but you can find them under 15W. My Quieter3Q for instance is fanless & runs on a Celeron in just 15W. I love it, but one annoyance is, it does not come back on by itself after a power interruption.
Additionally, my home Pi4 sits in a metal case that acts as a heat sink so I don't have to use a fan at all. That translates to:
- additional energy savings
- more or less eliminated need to clean out dust or eventually replace a fan
- no fan noise, a massive boon if you live in a small apartment and don't have a closet or basement you can toss the server into for noise insulation
I suppose if I did serious number crunching on my home server, I'd need something beefier... but I've been running a VPN, a Minecraft server, a streaming media server, and a DNS server on my Pi4 for more than 3 years now. Only during media scans do I feel any slowness.
If you need to pull 50W from a mini PC constantly, you probably can't run that same load (without horrible latency, throughput and stability issues) on a 15W ARM SBC to begin with.
But the Pi also needs to run much longer under full load to achieve the same as a modern mini PC, so it might be still canceled out in terms of total power use.
Raspberry Pi chip sets are always older (less efficient lithography/structure size) ones, as they take over the ones currently being phased out for industrial use (so they get them cheap).
Those have a hard time to compete with e.g., a modern Intel N100 CPU which has a TDP of 6W but at the same time 4 cores with a max freq. of 3.5 GHz and can even use DDR5 (or LPDDR5 for low power) and is available in many form factors, often fanless with a metal body as cooler at about 150€ (if lucky) to 200€ and those models then even including (often multiple) 2.5Gb Ethernet ports and NVMe M.2 slot.
That makes it at least for me an easy choice, and I am indeed looking out for using less power but still getting stuff done somewhat quickly.
