normal temp of RB912??

I have an rb912uag-hpnd-outdoor, connected to this antenna http://www.wireless-instruments.com/en/produkty/14/22/antennas-5-ghz/mimo/sector/wibox-sa-m5-90-17hv.html

the problem is that its problem is getting very hot on the burst client-use time ( on evenning ) it reahcs about 55C for just 4 clients.

you can see the attached image.
where I have heared that this board can withstand about 60 clients.

is 55c a normal temperature for rb912?
Can I reduce the temperature to save the board from being damaged?

what is its maximum accepted temperature?

regards
rb temp.png
rb temp.png

the board is not too hot when there is no download over it
temp2.png

Our 912’s haven’t broke 39c under heavy load.

What is the ambient temperature that the box is in?

How much is the ambient temperature?

Maby a ventilator is the solution of this

ambient temperature is important but most important is what data-rates are used by wireless interface. Lower data rates usually come with higher transmit power. To overcome this, get better link quality.