Are you guaranteeing that 120mW is safe for this hardware, since I have not read about anyone who is running at that level? Have you ran this level for any significant time, and have used your own router as the beta test for hardware failure?
I am not an Asus engineer and until THEY provide a(n official) response that says what is safe (see my updates in my other post which include comments they made in an e-mail i have received), nobody here can guarantee anything, especially since some components may get hot inside the router that won't always be (at least not fully) evident from touching the case.
80mW or 120mW is typically nothing unusual in other routers, but since this is a new deisgn we can NOT compare it (on an apples to apples basis) to, for example, at least one other firm's router design (running Tomato on a WRT54GL) that easily worked fine with 250mW (or more) for years in Europe - as per the link I posted last time.
http://tomatousb.org/tut:increasing-wrt54g-transmit-power
Regardless, Asus also should be responsible and limit the maximum calue to what is safe and not just go by the FCC limit, assuming 500mW (whiuch the current firmware allows) is unsafe (something which, again, I am not qualified to answer).
Again, the RT-N66U design is different and I do NOT claim to be an expert.
I will wait for Asus, or a qualified expert, to tell us.
As someone noted, for those who do experiment, there is a warranty for 2 years.
Refurb is not an issue IMHO since the refurb (if it is a true 'refurb' and not used) will be newer than the unit you're sending in.
I am not advocating any levels since I don't want someone to come crying to me.
For my needs (my home and my wifi adapters), if firmware xxxxxx102 is as good as 90 again, I won't need to bump the level at all.
The OP has issues when using it with the 40mW setting (not sure how large his place is or the environment and construction / design of the living space he is in. This is where TX power levels could help (or at least rule out the power level as an issue before buying an antenna that may do nothing).
All that being said, if everyone is supposed to keep it at 40mW to be safe, then why even have an adjustment (not even talking about 500mW, just talking about 80mW e.g.).
Once again, Asus did not provide a clear answer yet. I may reply to the
e-mail I got an push (again) for a safe level.
If I find 40mW in xxxx102 is not enough, I will experiment with bumping it and be happy to share my experiences here for others to draw on.
Keep in mind also that individual router usage (i.e. CPU usage), from user A to user B e.g., can also have an impact on temperatures to a certain extent. However if neither user A nor user B is taxing it with heavy loads, it should not be a significant factor from one user to another.
Again, adjust at your risk as I said a few weeks ago...
PS: Hopefully Asus did some testing at design time and took temperature measurements (they switched frrm a fan to a large heatsink - which limits hardware failures due to fans breaking down), so they presumably took measurements along the way.
Maybe they can use this to provide guidance. After all, they offer the feature in the stock firmware.
EDIT: The DEFAULT power in Asus firmware 102 is now displayed as 80mW in both 2.4 GHz and 5 GHz.
I guess this is the optimal value the router is tuned to by default that they referred to in their e-mail...