How to choose a NAS CPU? N100 and J4125 each took half a year. What really widened the gap was not the running scores but these three things.

I currently have two Feiniu NAS at home, one is a Rainbow N100 small host I bought at the beginning of the year, and the other is a J4125 industrial computer I received two years ago. At first, I thought, since they all have four cores and four threads, can they be used? It was only after Jellyfin transcoded the card into PPT and ran the photo album face recognition all night that I discovered that the CPU on the NAS was not the same thing as the desktop computer.

This article does not include parameter tables, but only three judgment points that I have made in half a year.: Transcoding, Docker, power consumption. If you are now torn between N100 and J4125, just choose after reading it.

Let me first tell you how I got these two machines.

The J4125 was a second-hand purchase. It has dual Gigabit network ports and two DDR4 laptop memory slots. I inserted 8G into it. It was considered cheap at the time, with the whole machine and power supply costing less than 400 yuan, and I thought it would be sufficient as a download machine and cold backup machine.

Later, more and more photos were accumulated, and family members began to upload them to the photo album. Docker installations also increased from three to nine, and the shortcomings of J4125 were exposed. When I ran face recognition in the photo album in the middle of the night, the CPU was fully occupied and it took several seconds to click on the background of the web page. I just added an N100 small host with a single DDR5 16G, and installed Feiniu as the main host. I retired the old J4125 for off-site backup and download disk.

So this comparison is not something I calculated on paper. It is the two machines running side by side for half a year.

J4125 and N100, the difference in parameters is invisible

Just looking at the paper, the J4125 has four cores and four threads, and the N100 also has four cores and four threads. Many people think they are similar at first glance. In fact, the difference between single-core and core graphics is more than a whole generation.

J4125 is the old 14nm Celeron in 2019, with a turbo frequency of 2.7GHz ； N100 is Alder Lake-N in 2023, which can reach 3.4GHz. On a single-core basis, N100 is almost 60 to 70% faster than J4125. Don’t underestimate this gap. For web interfaces such as NAS backend, Synology DSM or Feiniu fnOS, most actions are handled by a single core first.

The nuclei are more obvious. J4125 is UHD 600, an old guy from 10 generations ago, and the video hard decoding only reaches HEVC 8bit. ； The N100’s 24EU core display and AV1 decoding are all done for you. It doesn't matter to an ordinary NAS that only reads files, but if you want to use it to transcode and watch movies, this step directly determines the experience. I will discuss this in detail in the next section.

If you only do SMB file sharing, J4125 and N100 are enough. The bottleneck is not in the CPU at all, but in the network port and hard disk. This is why many old machines are sold cheaply, and the parameters seem to be fine, but you have to first think clearly about whether you can allow it to transcode and run containers after you buy it.

When I started using it, I actually tried it with the commands. Enter SSH on both machines and type nproc All come out are 4, knock again lscpu Looking at the model name, J4125 says Celeron J4125 @ 2.00GHz, and N100 says Intel N100. It is indeed easy to confuse them at a glance. What really creates distance is lscpu The string of flags in it: N100 has avx2, avx_vnni, video and image related instructions are also more complete, many of which are missing in J4125. In human terms, for the same task, one new instruction set can support several instructions. This is most obvious when running transcoding and photo album processing. Don't follow me and only look at the core number, that line of writing is the least nutritious.

4K transcoding is the real watershed moment

I figured it out through a Jellyfin transcoding. At that time, I was using my mobile phone in the living room to watch a 4K HEVC 10-bit movie on the NAS. I turned on hardware transcoding on J4125, but the picture was still stuck every minute. I went into the background and took a look at the CPU. The core and graphics were fully occupied, and the bit rate dropped to around 8Mbps and was still unstable.

Switch the same movie to the N100 and use Jellyfin to convert it to 1080P. The CPU usage is about 40%, and the screen will appear within two seconds after dragging the progress bar. Both machines have the same Docker installed on Feiniu. The only difference is the decoding and encoding of the core display. Especially for new encodings such as HEVC 10bit and AV1, N100 can handle hard decoding, while J4125 can only be half-soft and half-hard in many cases.

There is a premise that many people ignore here: Jellyfin hardware transcoding also requires the /dev/dri device mapping in Docker, otherwise you will think that the core display is broken. How to install Jellyfin in Feiniu Docker, I used to do it Feiniu NAS uses Docker to install Jellyfin It has been written in that most people get stuck in the mapping step.

If you only watch 1080P original movies, or use a TV LAN to play them directly, transcoding will not be triggered at all, and J4125 is not bad at all. This pitfall is to ask yourself: Do I have the habit of watching NAS movies on my phone outside? Yes, N100 is preferred ； No, the money saved is enough to buy a hard drive.

Docker and photo album background, CPU is working behind the scenes

Docker on NAS does not have high resident memory alone, but once the task is started, the CPU will increase instantly. Immich face recognition, Feiniu photo album scraping, and Jellyfin poster generation, these all consume the CPU in batches and are not finished with just one click.

J4125 runs my regular qBittorrent, Syncthing, and AdGuard Home, and the CPU is usually only 10% to 20%, which makes it easy to see. But as soon as Feiniu Photo Album starts scanning new photos, the quad-core can keep you busy for more than half an hour, and the response of the background web page becomes obviously slower. Scanning the same batch with N100 takes less time and can be operated smoothly in the background.

Memory and CPU are often talked about together, but they are actually two different things. Open more containers, and memory determines how many you can open at the same time. ； But whether a single container task is fast or not depends mainly on the CPU single core and core display. If you are still not sure how many containers you can open, take a look first How many Docker containers can a NAS run? , that article calculated the memory account very clearly. ； What is Docker itself and the concepts of port mapping directory mounting? What exactly does Docker of Feiniu NAS do? I broke it and crushed it into pieces.

Don’t forget the CPU when it comes to photo albums: Feiniu Photo Album's face recognition runs on the local CPU. Although the N100 is not powerful, it is much faster than the J4125. I wrote about 40,000 photos in my house during the actual test, you can read it How to enable facial recognition in Feiniu Photo Album . So as long as your NAS is going to use photo albums and Docker, don’t buy a CPU that’s too old.

Accounts for power consumption and long-term power-on

Many people think that N100 consumes more power than J4125, but after all, its performance is much better. I measured it with a power meter and found that both machines use the same 2.5-inch mechanical disk plus an SSD system disk. The standby power consumption of the J4125 is about 12W, and that of the N100 is about 16W, with a difference of about 4W.

What's the difference between 4W and 4W? Assuming that the power is turned on 24 hours a day, the electricity is less than 3 kilowatt hours a month, more than 30 kilowatt hours a year, and the household electricity price is 20 to 30 yuan. This little money buys transcoding and a faster backend, which I don’t think is unfair. Conversely, if you're extremely sensitive to electricity bills, the J4125 is indeed cooler and quieter.

Fever is also mentioned by the way. The fan will spin when the N100 small host is fully loaded, but it is basically not noisy at ordinary times. ； I changed the J4125 to passive cooling and it feels warm to the touch. What really determines whether your machine is noisy or not is not the power consumption of the CPU, but the hard drive and fan. I have a hard drive noise problem How to silence a noisy NAS? After a round of tossing in, the bedroom party can be watched alone.

So regarding power consumption, my conclusion is very simple.: Don’t sacrifice performance for tens of dollars a year, and don’t use “power saving” as an excuse to buy a platform that’s too old. What really consumes electricity is the mechanical disk and the fact that it is turned on 24/7.

I also put both machines into the same weak current box. When the room temperature is 31 degrees in summer, the J4125's passive heat dissipation feels hot to the touch but does not freeze. The small fan of the N100 speeds up on its own. In fact, the sound is not as obvious as the mechanical disk. If you really want to reduce power consumption, setting the mechanical disk to sleep is like trying to reduce the CPU W. NAS hard drive always fails to wake up from hibernation I checked this night's diary. Don’t regard the 4W of CPU as the main contradiction.

How to choose? Just copy from the third gear.

I condensed the experience of the past six months into three sentences.

• Only downloads, backups, and SMB file sharing ： J4125 is enough and the price is cheap. You have J4125 now, there is no need to change just for the sake of changing.
• To run photo album face recognition, Docker ten or eight, and occasional transcoding ： Just N100, don’t bother with J4125, you will save time and mood.
• Requires virtual machines, Windows, and a large number of 4K transcoding at the same time ： N100 is just above the passing mark, and if your budget goes up, you can get enough for N305 or desktop-level platform.

For those who have already bought J4125, don’t panic. First, control the number of Dockers to less than three, and connect the video directly to the LAN without transcoding. It will be no problem downloading and backing up for another three years. If you are struggling with the "add money items" of memory and cache, it is recommended to read it first. Is it worth upgrading NAS memory? , the CPU has not yet been selected clearly, and the hard disk cache is added randomly.

In the end, I left J4125 in my old house as an off-site backup machine, running only rsync and qBittorrent. The CPU was less than 20% all year round.

This is where I fell in the first place: I knew I wanted to watch 4K, but I bought the J4125 on the cheap, and ended up spending twice as much. The CPU of a NAS is the same as that of a router. Before buying it, it is much easier to think about "what will it mainly do for me in the future" than to focus on a few cores and threads.