4 core or 6 core for low-power server

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I’m planning on upgrading my UnRaid Server.  I would like it to be low power but able to handle 10-12 docker apps (6 may be running constantly) and 2-4 VMs (2 may be running constantly).


Apart from the above use plan, I’ll have the following:


Motherboard: mini-ITX

RAM: 16gb 

# of Storage drives: 4-6 (including cache and parity drive)

PSU: 250 - 400


I am trying to decide on the type of processor to get. Would 4 core, 8 thread CPU be good for this planned setup or do I need 6 core, 12 thread?


Thanks in advance

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Posted (edited)

For VM's it would be Windows 10 (for momentary testing), Mac OS Mojave or Big Sur (for momentary testing),  1-2 instances of Linux (for constant running of Volumio, Raspberry Pi, etc.)


For dockers, I'll have the following:











Not looking for super high performance. Just want everything to run smoothly when needed.

Edited by TekDRu
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The problem with this question is simply that there is no "right" answer.  You can absolutely get away with a 4 core, 8 thread CPU with just the information you provided.  But if I inquire deeper about what you're going to be doing in each VM /  docker application and what your expectations of performance would be, there could be additional guidance.  And even then, knowing how to match those needs exactly with the software you're going to be using can be quite a pain.


Docker containers that are running server applications will scale performance based on what you have available.  The more cores, the more power.  Doesn't mean that any individual app won't work with less power, but those apps will run a bit "slower."  That could mean the UI loads slower, actions within the UI happen slower, and bulk operations (extracting files, compressing, encoding, etc.) could take longer.  But what's "fast enough" and what's "too slow" is impossible for anyone here in the community to tell you.  That is just something you have to decide for yourself.  In addition, what those individual containers will be doing, how many jobs they are handling, and how many users are interacting with them will further drive the need for performance.


The only two areas we can explicitly guide you are for localized gaming VMs and Plex docker containers.  What is specifically unique about those two use-cases is the need for real-time performance.  If you don't have sufficient CPUs for those applications, your gaming experience can have low FPS and have hitching/stuttering.  For Plex, insufficient resources means you can't transcode fast enough or will be heavily impacted based on the number of users you have.  You don't seem to indicate a need for either of these.


The main advice I can give you is that if you can afford to bump up your horsepower, go for the 6 core, 12 thread because faster is always better.  But if you are looking for someone to give you that silver bullet of "oh at 4 cores it is going to be horrible and at 6 cores it will be amazing" or "4 or 6 doesn't matter", you're not going to find anyone here that will be able to explicitly say that with confidence.

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Thanks Jon. I really appreciate the response and the advice. After reading your advice, I think I'll lean more to the 6 core for a longer lasting build.  I was just hoping to remain with a low power consumption setup.


Thanks again!!

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3 hours ago, TekDRu said:

I was just hoping to remain with a low power consumption setup.

In general, the newer the die type, the more efficient the rig is going to be, with the faster the specific model within the die type being more efficient overall. The quicker the chip can complete the tasks, the more time can be spent at idle with the disks spun down, which is the most efficient way to run. So, for overall lowest consumption you generally want the newest die available with the highest speed you can afford.


Efficiency is determined by how much work the rig will do with a given amount of power.

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@jonathanm  What do you mean by die type? I am not sure I understand.  How can I find a list of the newest options? Can you give me an example or some suggestions for intel.


I'm trying to upgrade from a very old setup running a atom, GA-D525TUD.  What I like about it is that it uses about 45w on idle.  I would like a more powerful setup but using close to the same amount of watts in idle.


Would these be good options:



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9 hours ago, TekDRu said:

What do you mean by die type? I am not sure I understand. 

Processor design family. As of this writing, "Rocket Lake" is the newest desktop intel processor. The Xeon on your list is "Comet Lake", which is the previous generation. The atom on the list is "Tremont", which is a totally different family, not directly comparable.


What I'm trying to get across is that idle power is going to be very similar if not identical between processors with the same layout. If you put together a system with the i5-11400T, measure the idle power, swap in an i9-11900k and measure again, the idle power will be virtually the same, but the i9 will draw much higher peak power under load while getting the work done that much quicker.


Since the processor is only a part of the total electrical draw of the system, it's important to finish the work as quickly as possible to allow the rest of the system to go back to idle as well.


Consider this scenario, processing a video file. Assume it takes a specific number of calculations to solve, the slower CPU takes an hour to finish, the faster one is done in 15 minutes. The CPU's take roughly the same amount of power overall to get that work done, assuming like I said they are from the same design family. The hard drives have to stay spinning the entire time, so the slower CPU uses 3 times more hard drive watts while the faster CPU is done and lets the hard drives go to sleep.


Also consider the total lifetime of the system. The faster the CPU, the more likely it will be useable in the future. A slower CPU will need to be replaced sooner, at a significant cost, since replacing the CPU generally means replacing board and memory as well. It's not usually wise to buy the very fastest CPU, but somewhere at the upper end of the speed range is better than the slowest model.



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8 hours ago, jonathanm said:

It's not usually wise to buy the very fastest CPU, but somewhere at the upper end of the speed range is better than the slowest model.

Thanks Jonathanm. That's a great explanation.  I really appreciate the info.  With this in mind and my use case, would you recommend an i5 or i7?  I started to look at some AMD Ryzon options like 5600GE and 4600GE. Still trying to narrow down my choice.

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