I just installed an RB2011UAS-2Hnd and when I was about to leave I touched it
It was burning hot; I checked the health monitor and saw 82C
Config: 2 active Gig Eth ports, and two Fast Eth, that’s all
12 routes, 69 F/W rules, 6 NAT rules, no mangling, no queues
The CPU was only around 4-6% at the time
I removed the rubber pads underneath it and placed it on top of metal cabinet so as to help dissipate the heat
Ten minutes later and the temp is steady at 80C, CPU 0-2%
The box feel very warm top side, and hot (not as hot as before) on its underside
the most common cause for overheating RB2011 are damaged radio amplifiers U700, U701, or soldering problems with U100 AR8327 chip, but
in those cases they never cool down. So much heat can give only damaged components, so most likely you need to return it for RMA. When board heats
up again, he can check wich component is hottest and it is worth a look in Routeros commands: “tool profile” (if usage is normal) and
“interface ethernet switch port print stats” , there is columns “switch1-cpu switch2-cpu”, if there are problems with CPU or PHY chip,
they always give thousands of “rx-fcs-error”.
Similar issue here, but I find a solution. In my case, this is faulty power source. When I replaced default power source with one of 24V/1.25A, RB temperature went down from 92C то 45С and router never heats up again
