AC86U overheating

[thedarkness]

Hi,
I'm running Merlin 386.5_2 on my RT-AC86U, since more than 2 years.

Today I've noticed that there's only one CPU in the dashboard.

Tools > Temperatures: 2.4 GHz: 50°C - 5 GHz: 56°C - CPU: 96°C

The router is idling, there are 12 devices connected in total, but I'm not doing anything on the network. I am not running any third party software on the router like Entware.

Logs:

Jun 17 19:00:12 kernel: thermal cooling_device1: turn off CPU#1
Jun 17 19:00:12 kernel: IRQ6 no longer affine to CPU1
Jun 17 19:00:12 kernel: IRQ28 no longer affine to CPU1
Jun 17 19:00:12 kernel: IRQ29 no longer affine to CPU1
Jun 17 19:00:12 kernel: IRQ30 no longer affine to CPU1
Jun 17 19:00:12 kernel: CPU1: shutdown

So, now it's pretty hot in my place - 31°C due to a heat wave - but my other passive cooled devices are doing fine, like my Raspberry Pi4.

The router is out of warranty, I purchased it 2 and half years ago.

The temperature is very scary, what should I do? The router has room to dissipate heat.

 

[eibgrad]

This is a long known problem w/ that router. Just a bad thermal design. Search the forums and you'll find plenty of others w/ the same issue and suggestions, ranging from using fans, to reworking the internal heatsinks. But frankly, if it's been running that hot for that long, it may already be too late to prevent eventual failure.

 

[Oracle]

As a minimum, put a fan behind it asap. Like - immediately. I hope the core is only in thermal protection shutdown without permanent damage.
You can see my topic and many others in the forum.

My experience with the RT-AC86U

Decided I'd setup a sort of online diary about my user experience with the Asus RT-AC86U, a.k.a. Wireless-AC2900. It has dual-core 1.8 GHz CPU, 512 MB RAM and for what I can tell, good throughput and good WiFi radios. (If looking for a router in 2022, turns out there are better options for a...

www.snbforums.com

 

[Darkje]

If you a bit handy get copper as thermal plates. I did it with mine and now it is running at 67 degrees. In a room that is 28...
I don't use fans. But for now I advice to use one to cool it down a bit.

 

[thedarkness]

Allright, thanks for the recommendations!
I have to purchase a USB Fan however.

Is there a way to replace thermal pad or something similar? I'm not very handy with this kind of work.

 

[thedarkness]

@Oracle in your post you wrote:

So I replaced the pads under the heatsink with brass and Arctic Silver paste.

I have extra thermal paste lying around. Is this something that can be done easily like on a PC?

 

[Tech9]

Is this something that can be done easily like on a PC?

No. You need new thermal transfer pads as minimum, about 2.5mm thick. The router has to be taken apart completely. It has screws under the label, clips around the edge, more screws inside holding one heat spreader, more screws holding the PCB, more screws holding the CPU and radio ICs heatsink.

Use a fan behind it as temporary measure, look for deals for router replacement.

 

[thedarkness]

No. You need new thermal transfer pads as minimum, about 2.5mm thick. The router has to be taken apart completely. It has screws under the label, clips around the edge, more screws inside holding one heat spreader, more screws holding the PCB, more screws holding the CPU and radio ICs heatsink.

Use a fan behind it as temporary measure, look for deals for router replacement.

Do you recommend a 120mm 800 rpm fan powered via USB or something else?

To be honest I don't want to replace this router, other than this temperature problem works perfectly fine and I'm not yet into the WiFI6 world. And the AX86U costs a lot more of what I paid the AC86U two and half years ago

 

[Tech9]

Do you recommend a 120mm 800 rpm fan powered via USB or something else?

I recommend router replacement. Overheating is not the only AC86U issue. On top of everything it has software issues as well.

 

[thedarkness]

I recommend router replacement. Overheating is not the only AC86U issue. On top of everything it has software issues as well.

Yeah, I get it. I meant what fan should I get to not kill this hot boi

 

[Tech9]

I would get the one pictured below and point it to the back side of the router. It will drop the temperatures you see to normal operating range. Powered by the router's USB is not ideal, but it will do the job. It's about $15 on Amazon.

 

[Tivi]

Allright, thanks for the recommendations!
I have to purchase a USB Fan however.

Is there a way to replace thermal pad or something similar? I'm not very handy with this kind of work.

Replacing the thermal pad is the way to go. I did it on both of my ASUS routers and the CPU temp dropped 25 C immediately. I don’t suggest the fan option. The issue is with the heat not transferring from the CPU to the heat sink. The passive heat sink itself is satisfactory.

 

[Tivi]

Hi,
I'm running Merlin 386.5_2 on my RT-AC86U, since more than 2 years.

Today I've noticed that there's only one CPU in the dashboard.
View attachment 41926

Tools > Temperatures: 2.4 GHz: 50°C - 5 GHz: 56°C - CPU: 96°C

The router is idling, there are 12 devices connected in total, but I'm not doing anything on the network. I am not running any third party software on the router like Entware.

Logs:

Jun 17 19:00:12 kernel: thermal cooling_device1: turn off CPU#1
Jun 17 19:00:12 kernel: IRQ6 no longer affine to CPU1
Jun 17 19:00:12 kernel: IRQ28 no longer affine to CPU1
Jun 17 19:00:12 kernel: IRQ29 no longer affine to CPU1
Jun 17 19:00:12 kernel: IRQ30 no longer affine to CPU1
Jun 17 19:00:12 kernel: CPU1: shutdown

So, now it's pretty hot in my place - 31°C due to a heat wave - but my other passive cooled devices are doing fine, like my Raspberry Pi4.

The router is out of warranty, I purchased it 2 and half years ago.

The temperature is very scary, what should I do? The router has room to dissipate heat.

Don’t waste your time and money with the USB fan. Fix the root cause which is the heat pad between the CPU and the heat sink. It takes about 30 min but then the CPU temp drops 20-25C immediately without any active cooling. I could not find the exact copper thickness so ended up using the pad below which worked perfectly and probably easier than the copper.

Thermalright Thermal Pad 12.8... https://www.amazon.com/dp/B09DT1GVD9/?tag=snbforums-20

 

[Tech9]

Replacing the thermal pad is the way to go.

I agree, but the process is outside of comfort zone for most users.

The issue is with the heat not transferring from the CPU to the heat sink.

Correct. Lowering the heatsink temperature helps though. Temporary.

 

[thedarkness]

If opening an AC86U is similar to AC68U (video here) I'm comfortable to replace the pads!

 

[Tech9]

Yes, very similar. Get what you need first though. @Oracle did it recently:

Router temperatures

just ordered a new dedicated firewall hardware If you are planning to re-use the AC86U as Access Point, Asuswrt doesn't have VLAN's support and you'll lose Guest Network option. It is actually available in AP Mode GUI, but it doesn't separate Guest Network connected devices from your main network.

www.snbforums.com

 

[thedarkness]

Alright, I purchased the pad recommended by @Tivi - 2.5mm
My radios are fine, just need to change the CPU pad.
Thanks for the help, I'll let you know

 

[Smokey613]

What command can I use to check the temps on my ac86u node. I have ssh access to it.

 

[Tech9]

What command

Try:

cat /sys/class/thermal/thermal_zone0/temp

 

[Tech9]

My radios are fine, just need to change the CPU pad.

Change them all. The original pink ones leak silicone. You'll find large oily spots on heatsinks. Some pads may rip when you lift the heatsinks.