Well that noise floor shoudl be okay...
Channel Noise Floor is above 80. If Noise Floor is lower then too much non-802.11 interference
How is your Channel Frame Retry Rate %? it is below 30%.? If higher then too much interference...
You can check it by running
show ap active ip-addr <ap ip address>
Guess you already know that :) but still put it....
How is the channel utilization?
You should be able to see it on the dashboard but if you got RF protect license and can put an AP on spectrum analysis on where you see more issues you can then use the channel utilization trend graph to see it... or if you got an air checker of fluke or something like that you can see that right away with it :)
Check that the channel utiliization is not that high....
Also How many users are plugged in one AP on the 5ghz band? what kind of apps you running over wifi? are you using VOIP phones and stuff like that? or running HD video over wifi? those things affect how many users its recommended to have in that band on one AP.
For example if you using VOIP phones is not recommended to have more than 20 users on one AP per band...
Cheers
Carlos