AC86U Heatsink Mod

[slurmsmckenzie]

AC68U has a firmware bug/limitation when used as AiMesh node - LAN ports are limited to 1/2 speed. Also, not every firmware offers stable Media Bridge mode on AC68U - you have to experiment. The ideal situation is AC86U as single router. Second best is AC86U as router and AC68U as wired Access Point. Wireless AiMesh with AC86U and AC68U may or may not work for you. Expect additional complications if your AC86U is running Asuswrt-Merlin - AC68U may not want to join AiMesh.

Thanks again, this encourages me to think about stock firmware on both devices in that case. I will see how it goes! Might give AiMesh a miss for now though.

My post was meant to encourage @slurmsmckenzie to give pfsense a try, not derail this discussion about thermal management of Asus routers.

Much appreciated, thank you!

Now you are going to do Guest Network with Asus routers in Access Point mode?

I have limited knowledge of all this but I assumed the VLAN / guest network comment was related to using old Asus routers as APs rather than the pfsense side of things. I was thinking that it could still be a useful starting point even if the old routers are restricted - a first step I guess. But I worry that I have caused this thread to be derailed, sorry all Still, hopefully the discussions might be useful to other AC86U owners in future. I'll take what I have learned and have a play

 

[Tivi]

Thanks for the info. I am the original owner for the one that is running at 97-98 since 2018 and I only recently observed the CPU turn down due to high temp. Otherwise it has been very stable. I got the second one from ebay last year (also 2018 model) as well but running at 86.

A few days ago I got a refurb model from Amazon that was made in 2020 and running mid 60's. So looks like they used slightly different thermal solution now.

Let's see if I can salvage the one that is running hot and extend its life for a few more years. I will let you know how much the temperature drops after the thermal pad replacement.

I received the Thermalright thermal pad from amazon yesterday and replaced the one on the CPU last night.
The temperature went from upper 90's C to 65. I am quite impressed with the result.

 

[slurmsmckenzie]

I received the Thermalright thermal pad from amazon yesterday and replaced the one on the CPU last night.
The temperature went from upper 90's C to 65. I am quite impressed with the result.

View attachment 39285

Great result! So that was a straight swap for the 2.5mm Thermalright? Perhaps I should have done that rather than messing with copper!

 

[L&LD]

@Tivi, could you provide us a link to that Thermalright product? Thank you.

 

[Tech9]

I am quite impressed with the result.

Yes, the pink color pads used by Asus leak and dry out over time. You perhaps had a big oily spot on the heatsink.

 

[Tivi]

Great result! So that was a straight swap for the 2.5mm Thermalright? Perhaps I should have done that rather than messing with copper!

Yes. The hardest part of the process is to open up the case but other than that not too complicated.

 

[Tivi]

Yes, the pink color pads used by Asus leak and dry out over time. You perhaps had a big oily spot on the heatsink.

Yes. I cleanup both the board and the heat sink with alcohol.

 

[Tivi]

@Tivi, could you provide us a link to that Thermalright product? Thank you.

Thermalright Thermal Pad 12.8 W/mK Non Conductive Heat Dissipation Silicone Pad for PC Laptop Heatsink/GPU/CPU/LED Graphics Card, Silicone Thermal Pads 85×45mm Silicone Grease Pad Multi-Size(3.0mm) https://www.amazon.com/dp/B09DT32TH3/?tag=snbforums-20

this is the link to the 3 mm version. I bought the 2.5 mm but I suggest the 3 mm. That way you can also replace the pads on the wifi chips. The 2.5 is too thin for those. This pad is almost like putty so you just need to fill the area between the chip and the heat sink as much as possible to improve heat conduction.
One package is enough for 10-15 routers.

 

[Darkje]

After a bit more modding I replaced the fan, with a suction model.

Awesome

 

[LarryO]

I just want to add my own experience to the discussion. I am using AC68U rev 3. I didn't know that it was running hot until I installed Merlin. Supposedly 74C is not bad, but I never had equipment run that hot before, so I decided to do something about it. I took the device apart and added a graphite thermal paste to both radios and the CPU. That lowered the CPU temp only 2 degrees. So I hung two 80mm USB fans on the back. (Several models avaliable at Amazon for around $15.) The router is now running at 53C for a week. I can't go back and remove the thermal paste now, but this suggests to me that it was probably a waste of time. I also needlessly invalidated the warranty, Fans are cheap, easy, and effective.

 

[Darkje]

I just want to add my own experience to the discussion. I am using AC68U rev 3. I didn't know that it was running hot until I installed Merlin. Supposedly 74C is not bad, but I never had equipment run that hot before, so I decided to do something about it. I took the device apart and added a graphite thermal paste to both radios and the CPU. That lowered the CPU temp only 2 degrees. So I hung two 80mm USB fans on the back. (Several models avaliable at Amazon for around $15.) The router is now running at 53C for a week. I can't go back and remove the thermal paste now, but this suggests to me that it was probably a waste of time. I also needlessly invalidated the warranty, Fans are cheap, easy, and effective.

Did you just make a typo on the 68/86 side ??

 

[LarryO]

Did you just make a typo on the 68/86 side ??

No, it's AC68U. I know most of the discussion here is on the 86, but they have similar issues.

 

[Darkje]

This is my 68 as node:

CPU temperature : 65C