My RT-AC86U Merlin 386.2 shows only Core 1 (Core 2 disappeared), High temp --> How to adjust to be a normal

  • ATTENTION! As of November 1, 2020, you are not able to reply to threads 6 months after the thread is opened if there are more than 500 posts in the thread.
    Threads will not be locked, so posts may still be edited by their authors.
    Just start a new thread on the topic to post if you get an error message when trying to reply to a thread.

JKP

New Around Here
Hi,
As per topic; My RT-AC86U Merlin 386.2 shows only Core 1 (Core 2 disappeared), High temp --> How to adjust to be a normal
My AiMesh System is...
AC86U...main router
AC88U...node #1...Ethernet cable backhaul
AC68U...node#2...Ethernet cable backhaul

All of them were applied Merlin 386.2
Usually number of clients are 35-52
Ambient temperature 28-35ฺฺ Degree Celcius, no additional fan

Many thanks for your suggestions.
 

Attachments

  • AC86U_Core1_.jpg
    AC86U_Core1_.jpg
    144.6 KB · Views: 97
  • AC86U_Temp_.jpg
    AC86U_Temp_.jpg
    94.9 KB · Views: 98

Wade Coxon

Senior Member
This has been covered at exhausting length in a few threads now. Here is one that is dedicated to the topic and should contain all the info and links you need:

In short, the 386.x firmware series introduces some new CPU hungry features, in combination with switching off some power-saving settings that result in pushing some rt-ac86u units over the line from "quite hot" to "too hot" due to a poorly designed thermal interface between the CPU and heatsink.

The heat issue was actually much worse on the initial 386.1 beta as there was an additional CPU WAIT feature that was disabled by default which caused a very steep rise in temperatures.

You can switch the power saving "Energy Efficient Ethernet" option back on via the command line, and you can also cut down on heat generation by using as few LAN ports on the router as possible (use an external switch if you need more connectivity).

Those measures can drop your temperature a good 10 degrees or so and get the CPU back into a safer zone.

To go any further, you can install an aftermarket fan to bring temperatures down, or in an extreme case, you can disassemble the router and fix the thermal contact issue, but that comes at some risk.

The info you need should be in that link.
 

JKP

New Around Here
Hi, many thanks for your advice about reduce the heat generation and heat reduction. I try to fix it as commented.
 

JKP

New Around Here
Update the result after installing 2 Fans (5V 60mm.) on AC86U backside and push-in airflow.
That's so a big improvement - decrease around 36-37 Degree Celsius.
Before: CPU temp...104 Degree Celsius
After: CPU temp...67-68 Degree Celsius @ambient temp 30-31 Degree Celsius....
:)
Both Core 1 and Core 2 are working fine.
Log file:
Apr 6 19:41:39 kernel: thermal cooling_device1: turn on CPU#1
Apr 6 19:41:39 kernel: CPU1: Booted secondary processor


3 Gigabit LAN port are occupied.

Thanks for your advice @Wade Coxon.
and give credits to all folks contributing in this thread...

Router temperatures

AC86U_Temp_2Fans Installed_.jpg
 
Last edited:

Tech9

Senior Member
Good job and fast reaction, @JKP. See what happens with copper shimmed CPU on AC86U and a fan:

Untitled_M.jpg


Why is this overheating happening I tried to explain in my post here:

 

mromero

Senior Member
This has been covered at exhausting length in a few threads now. Here is one that is dedicated to the topic and should contain all the info and links you need:

In short, the 386.x firmware series introduces some new CPU hungry features, in combination with switching off some power-saving settings that result in pushing some rt-ac86u units over the line from "quite hot" to "too hot" due to a poorly designed thermal interface between the CPU and heatsink.

The heat issue was actually much worse on the initial 386.1 beta as there was an additional CPU WAIT feature that was disabled by default which caused a very steep rise in temperatures.

You can switch the power saving "Energy Efficient Ethernet" option back on via the command line, and you can also cut down on heat generation by using as few LAN ports on the router as possible (use an external switch if you need more connectivity).

Those measures can drop your temperature a good 10 degrees or so and get the CPU back into a safer zone.

To go any further, you can install an aftermarket fan to bring temperatures down, or in an extreme case, you can disassemble the router and fix the thermal contact issue, but that comes at some risk.

The info you need should be in that link.
12 volt CPU fan derated to 5 volt using Merlin 384.19
asus-rt-ac-86u-fan.jpg
 

Latest threads

Sign Up For SNBForums Daily Digest

Get an update of what's new every day delivered to your mailbox. Sign up here!
Top