low power server build

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Hi all,

Its my first time posting and I hope this is the right community for this question. I lead a university research team working on building a solar powered Minecraft server. We are currently using a 100w solar panel powering a 12V50AH LiON battery connected to a HUNSN miniPC with an intel i5 1065G7 and a HUNSN BM27 mobo.

The idle draw on this is a very nice 15watts and with the server running (on linux) in performance mode we draw about 45-60w.

What we want to do now is build our own miniPC which will support undervolting and wake-on-LAN to see if we can get our power draw down as low as possible while still running the game. Anyone have any component suggestions for the ultimate low power server?

also if anyone is interested in our project you can check out at SunBlock One - Minecraft Bloc

cheers,
Bart

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University research team, huh? Then please, for the love of ${DEITY}, at least get your units straight:

The unit of power is 1 W (uppercase W).
The hour (in ampere-hour) is written with a lowercase h, so one ampere-hour is 1 Ah. (Upper-case H is the henry, a unit of inductance.)

Edit: Note that when written out, both the watt and the henry are written without inital capitalization to differentiate them from the names Watt and Henry.

A typical Dell/Lenovo/Fujitsu SFF office PC with Intel gen 8 or 9 CPUs typically idle at about 5-6 W, as measured at the wall, with a few powertop tweaks (or ~10 W out-of-the-box). I don’t think you can DIY anything better than this.

How will Wake-on-LAN help with power draw while still running the game?

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ah my sincere apologies to you and your deity for the mis-attribution of units. I will be more careful in future
 I thought I was on reddit there for a second :slight_smile:

It is an interesting point about the low idle of newer office pcs though I am not sure that translates to lower draws under load than DIY might be able to get running in performance mode (and especially if lowering costs is also important).

The server runs off a 50Ah (small h :slight_smile: battery and so the PC will shut down from time to time. We need the to get the PC to turn back on when the battery recharges. Thus the need for wake-on-lan.

We are designing games using solar controller, battery and system power data so our use case is pretty specific. I wondered if there would be some interesting ideas around low power server builds for this since every Watt saved (capital W!) translates into precious server uptime.

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search for UPS, you’ll find a lot of usefull info there (power-managment-wise) :slight_smile: also you’re probably not in unversity for electronics, so no point explaining the details.

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I don’t know about ${DEITY}, but personally, I accept your apology. :wink:

Those gen8-gen9 based office computers can be found used/refurbished on Ebay for ~$100 or ~€200. Again, I don’t think you can DIY anything cheaper (at least not with even close to the same CPU performance).

For better energy efficiency under load I guess newer CPUs are generally better though. You might have to experiment a bit, running some “typical” (and standardized-by-you) Minecraft server load, and measure how much energy different systems consume for the task. Neither idle power nor TDP will be good indicators for this.

Thanks!

Nooo
 Watt (the James Watt) died in 1819, so if you want to save him you are too late. Every watt saved though


Are you developing some kind of high-availability distributed server failover, or is the idea to just add stress to the players with an in-game battery charge indicator? :slight_smile:

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An Asus h610 CSM d4 something itx board with an alder lake cpu like the 12400 or 13400 can get about 4w idle with a sata ssd and it runs on 19v DC. It should be a lot more powerful on alder lake than your 10th gen so under load it would also be lower power.

This motherboard also has tons of options to configure. So you can experiment with lower power limits than the default 65w.

Don’t go for anything newer desktop hardware. For amd the only efficient option is the 5700g but you need an efficient board. Am5 CPU’s are more inefficiĂ«nt because of the chiplets and the new Intel arrow lake (285 etc) are also less efficient platforms in base consumption.

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Hmm, a solar panel connected to a 12V 600Wh battery? You already have DC power using that, so if you have an Electrical Engineer on your team, use that to get ridiculously low.

Other than that, I’d recommend a CPU in the 10W TDP range, soldered to a motherboard. An Intel NUC could be the answer here:

That specific model only draws between 5W - 26.5W, giving a worst case of ~22 hours of playtime (with a full battery).

Make sure you also buy a DC-DC converter. The newer NUCs should have a USB C connector for power, but otherwise a 19V boost converter is required from what you have. One easy way to solve that is to make a power delivery board and two batteries in series for 24V of power, and then just use resistors to get the power within reason. If you calculate the load proper, you’ll see how much resistance is required using the all-powerful law of Ohm.

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Now this is the sort of nerdy stuff that I love!

Given the ultra low power consumption need, my mind immediately jumps to ARM, but minecraft servers are highly dependant on single-core performance. It might be worth finding an arm SBC with high clocks (or something that overclocks well) and experimenting with that for a start. I know that WoL is pretty niche in the arm sphere, so if that’s a hard requirement, you might be out of luck.

Just giving my 2c. I will be watching this project with great interest.

In looking at your project page, it looks like youre using an inverter to power ac. It might also be worth looking at DC power supplies here, because you lose efficiency when you go DC → AC, and then lose a bit more going back to DC. Buck/boost converters are much more efficient.

It’s also worth mentioning that those COTS battery/inverter systems are awesome for regular folks, but for your use case, there’s probably a 5w idle draw from the internal components on that as well.

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love this thought
 thanks.

on the PSU – I would love recommendations. We are actually 12V DC-DC right now and I want to stay that way if possible. The inverter route adds an unnecessary intermediate step and we are going to stay working with. We are using a 30A MPPT solar controller and feeding the data to an arduino which feeds the Minecraft mods we are making.

Anyway. If anyone knows of a good efficient 12V DC-DC PSU that would be amazing. I have been reading that some PSUs can be kind of lossy and we are already finding that the CPU is the least of our worries when it comes to idle load for our current miniPC

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wait
 could it be that our no-name psu in the minipc is an inverter and we are losing power there? This is all we know from the specs -
Power Supply: DC100-240V AC/50-60Hz, DC 12V/3A.”

I guess this is some kind of switching power supply? I think we had better investigate this further because a 5W loss is huge here.

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yes and yes. The main goal is to make solar charged battery power a game constraint so players have to be careful in how they play (as well as being attentive to the weather here in Montreal :slight_smile:

But beyond that we hope to enlist of few more folks who want to build solar servers in different latitudes so we can create one distributed minecraft world sharded to different servers. But that’s a whole other epic project. This would be a great sort of project for schools around the world for instance.

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Welcome to the forum!

Before I get into the technical part, click / tap here more details

I want to say that L1T forum isn’t plebbit and r*dditors ought to adapt or get out, lmao. Most people who join the forum adapt and all is fine, but we don’t aim to be a replacement for that cesspool. I hope you will find wonderful interactions here, we tend to be helpful. Some of us have wildly varying opinions, but unlike plebbit, we respect each other and each other’s opinions, even if we disagree.

I run almost all my stuff off of 12V DC and convert to USB-C power delivery. The conversion to USB-C is lower than it would be for for DC → AC conversion. I don’t necessarily suggest you go out of your way to convert the things you run to USB-C (unless they already have USB-C power input), but it was an easy (and safe) way for me to regulate the power output.

I’ve ran my lab from a bluetti eb70s successfully. It wasn’t powered by solar, but just by the battery and I charged via AC. Now I run everything off of my old UPS with 3x 120W 12V bricks (they have a cigarette lighter socket). I’ve got cigarette lighter “bricks” (I’d call them barrels) that have USB type-C output that can give you 5V, 12V, 15V and 20V DC via usb power delivery. Buying the right type-c adapter, you can power most things with these voltages, including some SBCs. My rockpro64, odroid n2+, L1 KVM and ethernet switch are powered by usb-c to 12v barrel jack 5.5x2.1mm adapters, a.k.a. 5521 jack, my odroid h4, h3+ and hc4 are powered by a 15v usb-c 5521 adapter and my other rockpro64 NAS, my 170Hz monitor and my 2.5G switch are powered by 20V usb-c 5521 adapters.

I believe my eb70s has a regulated voltage output (I didn’t know at the time, but it will come in handy when I go full solar), but a normal lead-acid or AGM battery will not. This is why it’s important to get a regulated output and USB-C was an easy add-on for me and cheaper than getting a buck-boost converter and a step-down converter (these can only deliver so much wattage and I needed lots of them). But for a single device, you could effectively run a boost and step-down converter and be more efficient than AC converters.

The biggest problem with solar installations are absolutely AC converters, that have bricks or PSUs plugged into them, that then convert to DC. You lose 20% efficiency (at best) and their idle power draw sucks too. For large arrays and continuous systems, it’s not as bad, but for small installations, they’re not negligible. If your solar panel gives you 100W output on a good day, you can only use 80W (and that’s excluding about 1-2% loss on wire runs). And you need to feed all that wattage to your server and you won’t be able to charge the battery.

There’s a couple of ways to keep uptime:

  • add more solar panels
  • lower your consumption
  • add more batteries

The 1st option is generally an obvious choice, leading to more system inefficiencies. You charge your battery faster and provide enough power to your load, but now your array is over-sized, wasting more space and capacity.

The 2nd option is not so obvious and requires quite a bit of analysis (which is why people just go with the 1st). One obvious load is the AC converter, which needs to be dropped. The 2nd is an oversized server for the workload performed. Think of it like using a phone (with a keyboard attached if you prefer) to write a quick email, instead of powering on a 1500W server, start a VM, VNC into it, open a browser, log into your webmail and then write the email. One is obviously a lot of waste for something you can do with less resources. Same goes for many other loads, but you need to know what are the minimum specs you can get away with for your worklaod.

The last option of adding more batteries is expensive and not as sustainable (uptime-wise). You get to power your load for more time, but if you can’t charge your batteries in time, your server will shutdown. And now you have more Wh to charge with a small panel, meaning you need more sun time (which last I checked, you can’t really change without moving towards the equator).

Now onto your server. IDK what’s your working budget, but you can have a number of ways to go about.

  1. Get a SBC and power it with 12v - 20v straight;
  2. Build a PC with a pico-PSU;

My obvious recommendation (I’m biased) is the odroid h4, h4+ or h4 ultra. The difference is with a quad-core (intel e-core) n97 (it’s better than the n100 - turbos at 3.6GHz) vs an octa-core i3 n305 (turbo @ 3.8GHz). The ultra is kind of an obvious choice, IMO.

The H4 lineup has WOL on either of its ports (meaning you could connect a single small SBC to 1 of the ports, who’s sole purpose is to run the WOL command), but even better, the H4 has an auto-turn on on power-loss. When power is applied, in the event of a power-loss, the server starts back up, removing the need for a WOL server to begin with.

The even better thing about this beaut’, is that you can power it from the 12V battery with only a buck-boost converter. Raise the voltage to 15 or 19V and no matter the battery’s charge state (10v when low or 14.4v when charged), you get a constant supply of power.

IMO it’s more difficult to power things that require 12v constant from a 12v battery. You need a step-down converter (to get the voltage down to 12v), but when the battery goes under 12v, the voltage sent to the SBC also gets lower. A step-down converter can’t provide more volts than its input (so more amps will be gobbled up, which can kill some electronics and even the batteries), which is why I discussed about a buck-boost and a step-down in the beginning.

That means recommendations such as an odroid n2+ (which uses 1W at idle for me and about 5W at average load - for the whole package!) wouldn’t make much sense in this scenario (other than maybe as a WOL server for a higher-powered server if you already use an AC converter and don’t want to get rid of it).

The other option, which would also require a boost converter is to DIY a PC with a (19v) pico-PSU. There you’d get a lot more inefficiencies from the chipset and longer wire runs on the mobo, coupled with additional components (resistors, caps, etc.). But you’d also be getting more performance if you require it. You could use a downclocked (and down-volted) ryzen 3 or an intel T variant. Many mobos will have the same feature to power-on automatically.

If the PC you have doesn’t, then you should get the lowest-power consuming device that will just power itself up automatically on power input. The odroid n2+ does that and literally sips power, so that can be a great contender for a WOL server.

Your university might be interested in the Solar Protocol.

And maybe Low ← Tech Magazine.

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It’s kind of expensive but the MSI Cubi NUC with the i7-150u. 15w and 2 cores boost to 5.4ghz.

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Is it a project for the fun of building something? Or do you just want to optimise power use without having fun?

In the latter case, a mac mini might actually be your best bet. Though it does have the PSU built in. It might be a fun project to mod it to run on 12V DC?

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this is amazing
 thanks so much for the thoughtful reply. The odroid boards are a revelation and a build with that might be perfect for what we are doing. Clock speed is everything on a Minecraft server so I just want to make sure we can match the performance of our 10th gen i7 1065G7 with less power cost. Do you know if we can undervolt the CPU at all with the odroid setup? This is something we are interesting in messing with.

Just a quick note that solar panel and battery are running through our EPEVER 30A MPPT controller which does all the voltage regulation so we get nice stable and clean 12V DC straight to the PC.

Our solar gaming season is pretty much coming to an end in Montreal and we can barely charge the battery so the next phase is to reduce power consumption with an even more efficient PC (an odroid build seems the most promising so far) as well as adding one more 100W panel. I am scrambling at the moment to pick up black friday deals.

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The i7 seems to win by about 19% in single core geekbench 6 and 6% in single core passmark. The n305 wins by 21% in geekbench 6 and passmark by 20% in multi-core. I checked more sites and it seems like the i7 takes the cake in single-threaded workloads. The question then becomes, what’s your whole system power draw? 'Cuz with the h4 ultra, I doubt you’d be hitting more than 30W maxed out (with a single m.2 SSD, not counting other media, like 4x sata SSDs). Its idle power draw will depend on how much expansion you use (basically the drives you add and how many and if you’re using 1 or both eth ports).

I think the idle power draw is going to be higher on the h4 ultra than it is on my h3+ and I never looked at the idle power draw of my h4 (I have the base model). But I doubt it’s going to be above 10W. The board can be powered with anywhere from 11V to 20V DC. The recommendation is 15v 4A if you don’t use 3.5" drives, however, that’s just what odroid sells, you can get away with a brick lower than 60W on it.

Odroid claims headless idle for the h4 ultra is 4.5W (and 3.3W for the base model - I’d need to test that, because that’s not what it feels like to me on my UPS output). Desktop idle is 5.9W for the ultra (and 4.5W for the h4 base, I could swear mine is higher than that, but I need to check it on my bluetti all by itself + the usb portable monitor). My odroid h3+ used 13W at idle (with the ~7-8W portable monitor).

Nice, that takes away a lot of headaches.

Oversizing your setup (with panels) is never a bad thing to do. But I think your MPPT can take in way more than right now. Just make sure that the voltage output from solar (open circuit) never exceeds your mppt’s max allowable input, or you’ll fry it. Solar panels in the winter tend to produce more power on a really sunny day (because of the lower temperature).

When in doubt, put them in parallel if your mppt hasn’t reached the max amperage limit (also helps that when you put panels in series, they tend to work as 1 large ones, meaning any shadow / obstruction will lower the whole array’s output, while in parallel, you can lose one panel to a shadow and still get power from another).

The only “problem” I have with oversizing is the waste. It’s generally not a problem in residential installations (it’s fairly cheap and you get a roof that you can cover back-to-back), but in mobile applications (RVs, vans, trailers and such), you have a limited space to work with for panels.

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A series resistor to drop 24 V to 19 V would only be 19/24 ≅ 79 % efficient. Not to mention that it only works at one specific load. So it would not work for this application.

Just to be clear, a buck converter is a step-down converter (and a boost converter is a step-up converter). So a buck-boost converter can convert both down and up (i.e. it can handle an input voltage that swings past its output voltage).

This seems like contradictory information. Are you power the computer via a ~12 VDC (battery) in → 12 VDC out power supply, or are you using an inverter and a standard mains voltage PSU?

Or is it a dual input PSU that can be powered from either mains voltage or 12 VDC?

Yeah, absolutely investigate further.

I’m thinking single threaded performance is everything, rather than clock speed. You can’t compare different CPU architechtures (or generations) by clock speed.

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Based on the conversation here and some more research I have narrowed things down to

Odroid H4 with the N97 vs something like a Asus H610T with Intel i3-13100

For our purposes what we need is the lowest possible idle draw, good power efficiency for light loads (“normal” modded Minecraft play" and room for much less efficient heavy loads (even overclocking) for fast flight, boss fights etc


The N97 seems perfect at the low end but I am worried we will run into trouble at the high end. We already have a server with an i7-1065G7 which seems to have better performance overall than the N97. With the i7 we get some lag with fast flight (chunkloading is CPU intensive) on performance mode by its playable.

The whole idea of our project is to make the battery (as well as solar power data) part of the game. So if one player flies too much or too fast (for instance) they will drain the battery faster and make it more difficult for others to play, etc


So the trick with our server built is to get this power consumption balance just right where players don’t get frustrated by a server which down all the time but still have to be careful about their energy consumption. Its been a really fun project so far with some great gameplay moments.

thanks again to everyone who has added their two cents on this


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Take a look at notebookchecks list. It should give an idea of what will have a faster single thread performance and a low TDP. And you can sort by different benchmarks.

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Oh nice
 if I am reading this correctly the N97 scores really really well on single thread performance for its TDP.

Am I correct in thinking that TDP tells me nothing about the idle power draw however? Is there anyway to compare CPU on this? On the other hand, the CPU idle seems to only be a fraction of the system idle draw so what I really need is some mobo comparison like this maybe.