CPU temperature of about 84C in a room that is not especially warm
Temperature is relative, so saying "60°C over ambient" is more concise and more useful. If the room temp rises 1°C, so will the CPU, assuming the before and after conditions are both at equilibrium.
I don't have the same model as you, but I do have its PoE cousin, the CRS328-24P, and mine is running at 29°C over ambient with all four SFP+ ports filled and two PoE loads of around 5W each. Two of the SFP modules are unused but present, and two are actively in-use 10G modules. Here's the raw data:
Screen-Shot-2022-08-15-at-13.17.jpg
Should I be concerned about the temperature I am seeing?
80-90°C (absolute) is a pretty good threshold for getting worried. Electronics can run hotter, but it'll materially hurt the lifetime.
I like to see 60°C or less, if I can get it.
There are no fans in the unit
The CRS328 comes with two, but has spots for four, so the first thing I did on getting it was to put a full set of Noctuas in, all pointing the same direction so air comes in on one side and goes out the other.
The problem with leaving fan mounts unpopulated is that you can get eddies: air gets pulled in and is sent right back out an inch to the side, having failed to cross the heat loads. The empty spots should have blocking plates in them to prevent this.
That, or do as I did and put four fans in so there's no shortcut for the airflow.
is there a good power source internal to the CRS that I could reliably use for power?
I can't be certain of your model, but mine had headers for four fans, so MikroTik has at least one EE on staff who's thinking ahead.
It's not hard to check, and while lifting the lid technically invalidates your warranty, until you actually touch the PCB to plug in a fan, I wouldn't consider that a true violation.
After doing this mod, the warranty is, "If it breaks, you get to keep both pieces."
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