Fan Speed at 5k RPM

Hardware MikroTik hardware general
1

Hi everyone

I just got done configuring my new CRS310-8G+2S+ switch. Everything is working fine. 10G uplink trunk, VLANs, all as it should be.

However after running completely silent, the switch suddenly ramped up to 5k RPM and it’s been staying there for 10 minutes now.

[admin@MikroTik] > system/health/print
Columns: NAME, VALUE, TYPE
#  NAME                VALUE  TYPE
0  cpu-temperature        46  C   
1  phy-temperature        49  C   
2  fan1-speed           5040  RPM 
3  board-temperature1     40  C   
[admin@MikroTik] > /system/health/settings/print
    fan-full-speed-temp: 65C
        fan-target-temp: 60C
  fan-min-speed-percent: 0%
   fan-control-interval: 30s

As a test, I set target temp and fan full speed temp to 40 degrees. Now the fan is imitating a jet at 13k RPM.

It seems the switch is trying to be smart and using like 40% fan speed even though temps are well below 50 degrees. Is there any way to adjust that or do I just unplug the darn thing?

2

I disconnected the fan but now the thing is getting too warm, I guess. The RJ-45 SFP+ module is at over 70 degrees C and looping in and out of existence on the switch.

I guess this product just won’t work for me.

3

Indeed fan speed depends also on SFP modules temperatures. And yes, RJ-45 modules (specially SFP+, so speeds up to 10Gbps) tend to run hot, so yes, fans tend to run faster than needed for switch electronics.

A few users changed original fans with quieter ones while keeping adequate cooling effectiveness.
But it does seem that actively-cooled devices equipped with RJ-45 SFP+ modules are not fit for use in silent environment. Either try with passively cooled devices (but beware of potential RJ-45 module overheating (see placement recommendation) or actively cooled device with RJ-45 ports built in (it allows for better engineered cooling; in MT parlance any device with XG ports, e.g. CRS312-4C+8XG-RM).

4

Well, that’s too bad.

In that case I’ll try connecting the uplink to a 2.5G port to omit the SFP. That case I wasted only 60 bucks on this endeavor.

Now I got to find out what fans there are that I could use to replace the acoustic murder machine in this one.

I connected the trunk to a 2.5Gig port… but now my download speed from the NAS is a measly 100-140MB/s. So yeah, the whole investment still looks like a waste.

5

Try setting minimum fan speed to 15..25%. It should prevent router from reaching temperatures that trigger high fan speeds.

6

There is something wrong here. 1 Gbps will give You about 110-120MBbps. 2,5 should give you more than 250MBps. There is a problem/bottleneck somewhere…

7

I have ordered a Noctua fan. Should be here by Saturday, I hope.

I will try setting a minimum fan speed as high as possible depending on its noise level. The current fan is too noisy even at 10% IMO.

8

I think so too but what? The only difference is using a 2.5G port for the uplink rather than a 10G port. nothing else in the config has change. All ports are connected to the same bridge so should be using the switch chip. HW acceleration is on as far as I could determine.

9

Now we investigate.
First step is looking at the stats of all ports involved. Are there dropped packages? Retransmissions? Is it really syncing at 2,5Gbps? I know the port can, but did it? How were the tests made?

10

Take a look at the test results:
https://mikrotik.com/product/crs310_8g_2s_in#fndtn-testresults

Pay close attention to the “Ethernet test results”, Bridging, none (fast path), with 1518 bytes packages. It does 1264.2 Mbps. Quite a coincidence, no? I think there is something on your setup that is routing the traffic.

11

We can check all that once the switch is in use again. Right now it’s just an unusable waste of money :smiley:

12

Now you can mark this topic as solved.

13

Indeed, it is solved. Even with a Noctua fan, this thing is too loud. This will need a lot of frankensteining to make useful.

I literally do not comprehend who this product is for. Nobody uses 2.5Gig inside a datacenter… but for anything outside of it, this seems too loud. Small business perhaps, when you can put it into a closet. A air conditioned closet perhaps… but even is an island switch for workstations, this thing is unusable.

Boggles the mind.

Edit: I’ve ordered a 140mm slim fan. I WILL make this thing useful.

14

This device is even really disgustingly ugly btw. Noisy and ugly - best combination.

15

With rack ears attached and mounted inside a communication rack it’s not as bad :wink:

16

https://www.reddit.com/r/mikrotik/comments/16zezva/crs3108g2sin_and_inside/

Looks like a standard 4pin PWM connector. Noctua used to ship with resistor cables (AKA low-noise adapter). Can be bought independently or DIY.
Such a cable in between - even with the stock fan - could decrease the dBm effectively.

17

It decreases but not enough. I don’t think you can make a 40mm fan that is quiet. It just cannot move enough air if it spins on an acceptable RPM.

The 140mm fan should do the trick but that’ll require me to go after the thing with the angle grinder. This is going to be fun :smiley:.

18

As I said, in a itsy bitsy closet in an office I could see it. Everything beyond that is pretty much a “why bother”.

I mean any company that can afford to properly cable its office space can afford a 24 port 10G switch and doesn’t need this. 2.5G IMO is for people with homelabs.
If they only have those 8 employees, I’m not sure they have the office space for a dedicated network closet…

It just seems weird to me… a more sensible cooling solution or hardware than runs less hot would have opened the market tremendously.

19

I can’t say if it would make a big difference (I dont have this switch so I don’t know how loud it is), but: SFP+ modules for FO run quite much cooler, so if this switch was connected upstream using FO modules, it might not run fan at such high RPM. And that would then qualify as “desktop” switch for two mid-sized offices in a not-so-tiny business.