Good Morning
I’ve just installed a CRS212-1G-10S-1S+IN, with 5 Mikrotik sfp interface.
The gbic temperature is always over 70° C and one is over 80°, i’ve installed a supplementary fan and i’ve reached 75° C, it’s an harware fault or an installation problem?
The interface spf often go down and then return up after some second,Is this a known problem?
Thanks
I confirmed this some issue.
Reported to MT suport but, not answer actually.
Looks like as hardware bug 
in this switch.
Ticket#2015042166000641 - First bug report almost 3 months ago. (port flapping and packet loss)
However, there is still no solution.
if air temperature above 30 degrees this switch is not usable.
This bug is only in CRS212-1G-10S-1S+IN , not in all CRS models
I’m in italy and during this day we’re about to reach 40° so… 
I have the same problem with temperature on CRS212-1G-10S-1S+IN (no connection problems yet, but I have it for short testing time). SFP modules are very close each other. When the switch has full number of them (10) and they are turned on, overheating occurs. The temperature is going to 70-80°C (highest is on ports 5-6, of course) which is dangerously high, I think. There is no air flow between them. I think this is hardware design problem, SFP ports should be in one row only.
Unfortunately, this is the only Mikrotik model with 10 SFP ports, so we have no choice Mikrotik, please make 2nd revision with full length (one row) or with some cooling.
Other guys: There is a fan hole on the back side. Did somebody tried to open the box and install a fan there? Maybe the warranty will avoid - but better than burn SFP modules and have connection problems, isn’t it? Is there an official fan as an accessory? Is there a connector inside?
I came to the same conclusion. (design problem, sfp module temperature to high)
It was nice to see the version of 19 ", with spaced/separated ports.
And a more powerful processor (for small routing)
I’ve just open it - there is no power connector, at least I don’t see any on the upper side of the board. Well, external power supply for fan could be used. Distance between fan holes is 25 mm. I tried to use Acutake Fan25, but it is too small (25 mm is outer dimension, holes are only 20 mm far). I have just 40 mm bigger fans.
BUMP!
I hope Mikrotik will have a look at this heat problem, and/or develope a new many port SFP switch!
I have made a suggestion on this here:
http://forum.mikrotik.com/t/plenty-sfp-cloud-router-swicth-coming-soon/92637/4
Hoping for a near future announcement Mikrotik! 
Hello,
finally an answer from MikroTik:
Hello,
After fairly long testing period it seems that in some scenarios with various modules mounted in this CRS model there is possibility of the modules overheating a bit to much and starting to behave as you described.
This only happens with modules that are made for temperatures: 0C - +70C.
In such case active cooling is needed. For current devices we can describe what needs to be done to add required active cooling. Regarding our future batches of this model, it will get case redesign with active cooling to remove chances of any modules overheating.Regards,
Krisjanis P.
Hi,
Did mikrotik sent you the modifications to be made, i´m experiencing this issue with 2 CRS212-1G-10S-1S+IN. I saw that there is a fan hole in the back side, by the looks it looks like a 40mm fan.
Can you please post the directions or post it somewhere so i can download and make those modifications. I´m experiencing link loss especially on sfp8.
Thanks!
I added a fan but the problem persists.
It seems that the switch has a hardware bug
Does someone know if multi-mode transceiver heats less than mono-mode?