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by bri3d 662 days ago
A few notes (as someone who is pretty staunchly anti-Pi-as-a-server, I end up having this debate often, and I do think there are reasons to do both):

* A Pi will sit much lower in total power consumption than almost any used PCs if both are doing effectively nothing (ie - simple, spiky tasks like filtering DNS, serving static content from RAM, etc.). You need to be doing something with the system before a PC server comes out ahead, and most people using a Pi as a home server... aren't.

Compared to a modern low-power x86 PC system, the difference isn't meaningful, but if you're buying used stuff 3 generations back, the difference becomes somewhat meaningful in terms of electric cost (on the order of tens of dollars per year, which is significant for hardware which cost tens of dollars to start with).

* The Pi of course has GPIO, SPI, etc. exposed, so you can use it as a nice "hybrid-IoT" device where it's a home server _and_ a sensor aggregator, for example. And the hat ecosystem, while generally insanely overpriced, is convenient.

Now, the moment you're running K8s/Docker or a real compute workload (security camera image recognition, etc.) you should probably move off of the Pi and onto something nicer, indeed. I absolutely never understood people running clusters of Pis or those goofy multi-Pi carrier boards. Just buy a real PC.

4 comments

> A Pi will sit much lower in total power consumption than almost any used PC

For electricity consumption, beyond the wallet, it actually seems that hardware should have a lifespan on the order of decades before electricity consumption savings offset the environmental impact:

"For laptops and similar computers, manufacturing, distribution and disposal account for 52% of their Global Warming Potential (i.e. the amount of CO₂-equivalent emissions caused). For mobile phones, this is 72%. The report calculates that the lifetime of these devices should be at least 25 years to limit their Global Warming Potential." —https://wimvanderbauwhede.codeberg.page/articles/frugal-comp...

Rather than buying a new Pi, repurposing a 5-year-old laptop has advantages if this something one cares about. Desktops are quite a bit more hungry (I've heard this got better in recent years), but I can attest that a 2012 laptop still functions very well as a server, easily better than a 2024-era Pi. Probably I'll replace it in the next 2-4 years (so at ~15yo) when my current laptop finally will have given me enough grief (my inner grandpa complains they don't make 'em like they used to), and I'm not saying others must optimise for climate alone either, but it's something to consider when deciding on a good balance

Environmental impact is not the main concern when it comes to power consumption. Main concern is how long will it work on a battery before a maintenance person can come by and switch the battery or if the sun will come out and start charging it again.
To illustrate a Lenovo Thinkcentre m720s idles at 9W! Intel i5-8500 (6C/6T), 8GB DDR4, 256GB NVMe SSD. It cost $120.
In order to begin to make a valid price comparison to this used (ie, not new) PC, we'd also need to know how much a used Raspberry Pi system would cost.
The RPi secondary market is a bit nuts; there's minor scarcity at times, plus the fairly strong brand, so people list them at their original MSRP all the time. No idea how many move at that vs. get low-balled.

At some point, dealing with reselling vs. just throwing in a bin (either back-of-the-closet storage or garbage) just doesn't make sense from a time/money perspective.

Go to ebay.com. Search for Raspberry Pi 5 or 4. See actual market prices by filtering to sold listings. Add cost of case, power supply, storage, maybe even active cooler.
> I absolutely never understood people running clusters of Pis or those goofy multi-Pi carrier boards. Just buy a real PC.

A bunch of Pis allow you to run multi-node clusters on the cheap. If you're just experimenting with Kubernetes/Nomad/whatever, you don't need a lot of resources, just multiple nodes. It's easier and depending on config potentially cheaper than getting a beefier mini PC, throwing lots of RAM, and running VMs.

Can a node be a VM?
> * A Pi will sit much lower in total power consumption than almost any used PCs if both are doing effectively nothing (ie - simple, spiky tasks like filtering DNS, serving static content from RAM, etc.). You need to be doing something with the system before a PC server comes out ahead, and most people using a Pi as a home server... aren't.

That's not necessarily true since the Pis are particularly terrible at idle power consumption. E.g. the "power off" state consumption shown in the article is actually higher than the idle consumption of some low-power Atom/Celeron x86 chips. The Pi is just terrible at power management.

Citation needed?

Pi 2 and 3 typically sit at 200 mAh and 230 mAh, Pi 4 is not far away. Zero 2W can go down to 96 mAh.

https://www.jeffgeerling.com/blogs/jeff-geerling/raspberry-p...

https://www.jeffgeerling.com/blog/2021/disabling-cores-reduc...

I don't see any x86 system approaching those numbers.

FYI: mA, not mAh.

milliAmps (mA): This is a measure of current flow. Think of it like the flow rate of water through a hose. It's the same kind of unit as something like liters-per-minute is: Where mA is a measure of electrical current flow through a wire (or a device or whatever), liters-per-minute is similarly a measure of the flow of water through a pipe (or consumed, or whatever).

milliAmp-hours (mAh): This measures how much current a something like a battery can supply over time. Imagine it as the total volume of water a hose can deliver if left on for an hour. If a battery is rated at 1000 mAh, it means it can provide a current of 1000 milliamps for one hour, or 500 milliamps for two hours, and so on. To use another water analogy, mAh is like describing the volume of water that is inside of a bucket.

The terms are not interchangeable.

I understand these things.

If a Raspberry Pi draws 200 mA for one hour, I think it's reasonable to say it has drawn 200 mAh.

It is not reasonable, because you did not specify enough information for the reader to draw that conclusion.

> Pi 2 and 3 typically sit at 200 mAh and 230 mAh

200mAh? Over the course of an hour? A day? A fortnight? Just one time, to kickstart the internal perpetual particle accelerator and continue infinitely without additional input? The phraseology used could have specified this information, but it did not do so.

One may wish these units would mean something other than what they do mean, but reality is simply not that way.

We aren't generally free to invent our own scientific nomenclature, or at least we aren't free to do so if effective and meaningful communication is a goal.

In TFA they are quoting a whopping 3W on idle for the RPi5 (just search for "idle power"). I have a Celeron system that idles _measured at the wall_ at 1.8W, including 8GB of LPDDR3 and a 4TB SATA SSD. Since I measure at the wall, I'm including transformer losses, which is not usually the case if you just measure current at the USB level as you seem to be doing.

They are also saying that the RPi5 in the default power off state (which is not even a real power off) it stays at 2W.

This matches my own results from the RPi4, where I had difficulty getting it to idle at less than 3W at the wall. While my x86 result is _out of the box_ with an standard openSUSE install.

The (desktop) RPi devices are just TERRIBLE. Cheap, small, have multiple GPIOs, but terrible power-wise. The µc RPis are another story.

What are the keywords to search for to find these Celerons? I assume they're ye'olde business pseudo-light terminals? Laptops are not bad, but desktop machines have easier connectivity.
I have a ASUS PN40; on this thread they also mention some N100-based ones which are more powerful. Distrust any result taken with Windows.
I might just buy one now because I find your wall-power results extremely surprising. My results with basically any mini-PC have been similar between Linux and Windows at minimum idle power; the Windows installs jump up off idle more often but I haven't seen a significant difference in the troughs. The Energy* and other reviews of PN40 indicate ~5W idle, which is more in line with NUCs and everything else I've ever seen from a mini-PC.