Hello!
CRS326-24G-2S+RM
Are there built-in fans for cooling? Can I have pictures of the open case inside the switch?
Added the case inside photo https://mikrotik.com/product/CRS326-24G-2SplusRM
No fans
Is it possible to put the fans yourself?
And then do not like what temperature, will warm up and then break. Without good cooling, the switch is bad. Now I’ve got CSS326-24G-2S + RM, and it also has no fans, and the CPU temperature is always 57 C, although it’s installed in a server with good cooling.
I guess the PCB has fan pins somewhere. But you obviously loose the warranty.
The PCB does not look to have any fan pins on it.
57 C is normal temperature. You do not need any active cooling system. Operating temperature for marvell chips is usually within -30 - +85 C. If you worry for high heating, you can just to glue small passive heatsink to processor.
the cpu already has a small heatsink secured with springs and heat conducting element. i just took apart one to take pictures, will post some images soon.
the big-a** heatsink is on the 3 pcs of marvell 88E1680-LKJ2 PHY transceivers.
i put the box under load (500Mbps full duplex traffic) via external traffic generator, but as far as i remember it was still around 57-58 C.
Traffic via CPU or only via switch matrix? You use this device as a router? Under RouterOS?
traffic via the CPU, i wanted to see how much i can squeeze out from the marvel CPU. it is better than CRS125, i could get 900Mbps traffic routed with minimal packet loss. i was obviously using RouterOS 
I believe yes, the Prestera platform have two core ARM v7 @ 800 MHz, so it can be as powerfull as bestseller RB750Gr3. But probably without hardware IPsec. Can You check this?
If you’re worried about it, bolt a small fan on the obvious location on the back where a fan could go, with the fan blowing air into the box. Mount the fan on the outside and power it from an external power source, and you could do this without ever opening the box. Then ideally block off the vent holes on the back on the section opposite end from the power inlet (the right side as viewed from the front - or if you prefer, the light end).
here you can find photos and a small post on the CRS326 and the marvell SOCs used in it.
https://tikguy.wordpress.com/2017/08/17/meet-the-crs326-24g-2srm/
Great write up, thank you doneware !
The temperature of my CRS326 is CPU temp 76°
is that a problem?
802.1ae MACSec support – to provide effortless link level encryption
And it would be nice if RouterOS actually implemented all the bells and whistles that are in the hardware. 
The same issue with me. The temperature of my CRS326-24G-2S+ CPU temp = 74°
Is that a problem? Also there is a lot of Rx Overruns Errors.
Switch is located at Datacentre with approriate cooling. Firmware is SwOS 2.9.
The same situation:
CRS326-24G-2S+ CPU temp = 74°
Three problems with CRS326-24G-2S+
- CPU temperature: 76°C - 78°C in room environment, 71°C in cooled env.
- Port flapping
- SFP+ issues when connecting between Mikrotik devices
Just in case anyone else gets this and reads this old post, Mine was running about 67 at idle in a full 6u network rack. I installed a fan and it went to 37 under load, but I still get TX/RX Pauses when using a 10m Cisco Active Twinax between it and another Mikrotik switch. I see this same issue on the other switch with 3m cisco Twinax connected to my ESXi host. I paid 8.00 for the fan assuming labor Mikrotik could charge 20.00 more for this switch and provide adequate cooling.
Which fans did you choose and how did you install them?