Just did a fan mod on my ASUS RT-N66U last night. I was tiring of the 2.4Ghz radio dropping connections constantly. My reported temps weren't outrageous at all (in fact, I'd say at 57° C and 55° C, they were pretty low compared to others), but I've already eliminated as many other factors as I could. So, if it is a hardware issue, I'd rather try a $10 fan first before investing in a new router.
I purchased this USB 5V fan:
http://www.amazon.com/dp/B00G05A2MU/?tag=snbforums-20
I marked out a pattern on the top cover of the ASUS case using a fan template, then drilled a bunch of ventilation holes. I mounted the fan on top of the case, blowing out. Got everything mounted back up on my network board, and powered it all back on.
The results:
Code:
Radio Before Fan After Fan (High)
2.4Ghz 57° C 40° C
5 Ghz 55° C 39° C
A few additional thoughts about this project:
1. I know there's plenty of debate about the need for more cooling, and that several people with much more insight than myself have weighed in on the opposite side. Like I said above, I was running out of options for addressing the 2.4Ghz radio problem, and this is a low-investment stab at a solution. If it doesn't work, no big loss.
2. I don't claim to be smarter than an ASUS engineer...but for a passively cooled router, the physical layout is pretty disappointing. The router is designed to lay flat or sit upright, but all the vents are on the back and sides. Additionally, the mainboard almost seals off the heatsink (which is mounted on top) from those vents. And, of course, heat rises.
3. Just a few changes would (probably? maybe?) make a difference -- putting some vents on the top so that the heat radiated by the heatsink can escape directly rather than being absorbed into the plastic case. Or making the case slightly larger so that there is better airflow from the front of the case to the back of the case. Maybe ASUS tested this stuff and had a reason for doing it the way they did. But it's still surprising to me. I understand the reasons to do passive cooling instead of active cooling, but not the reasons to do passive cooling in the manner they did, unless it was really just an accountant's decision that it was good enough and they weren't going to retool the case after dropping the fan from the first version.
4. 120mm barely fits on the case, as you see. I would probably do this again with either a single 92mm fan or dual 80mm fans. My purpose for using a 120mm fan was to move as much air as possible as quietly as possible, and I did manage to make it fit.
5. The fan switch has 2 intermediate speed settings, so I plan on testing those lower speeds to see how it affects the temp/stability of the router. The router is in our work/project room, so absolute silence isn't necessary, but less noise and power usage is always good.
6. I tested the fan's power draw using a little USB power meter and found that it draws less power than the external USB drive I previously had plugged in to the router, so I'm not too concerned about the load on the router's power supply. That said, I did order one of those ASUS EEE-PC power supplies just in case, since I have seen several posts about the original power supply crapping out.