Router temperatures

Donga120

Regular Contributor
AC86U, use to be on around 72C - 76C in a room with ambient temp of around 23C. Bought a 5V 140mm Noctua fan (Yes I know far too big) but temps are now lower than 45C on the CPU. Fan is too big really, and its a little noisy if sat by it, but for me it's a non issue, just need to clean it once every 2 months or so.

FYI: Running 384.19 as doing some debugging with my network
 

bbunge

Part of the Furniture
AC86U, use to be on around 72C - 76C in a room with ambient temp of around 23C. Bought a 5V 140mm Noctua fan (Yes I know far too big) but temps are now lower than 45C on the CPU. Fan is too big really, and its a little noisy if sat by it, but for me it's a non issue, just need to clean it once every 2 months or so.

FYI: Running 384.19 as doing some debugging with my network
Your firmware is way out of date and a security risk to you. High temp issues do not exist with either Asus or Merlin for the AC86U now.
 

Donga120

Regular Contributor
Your firmware is way out of date and a security risk to you. High temp issues do not exist with either Asus or Merlin for the AC86U now.

I know, but figured i'd risk it for a day for testing purposes. I am back on 386_3_2 now anyway
 

Tech9

Part of the Furniture
High temp issues do not exist with either Asus or Merlin for the AC86U now.

AC86U overheating issues are hardware related, not software. It overheats because of the way it's made. CPU wait disabled on some Asuswrt versions just revealed the issue. AC1900P from 2017 also has the same hardware flaw like AC86U around the same production year - 2-3 years use at high temperatures makes the thick thermal transfer pad hard and dry. Older routers have 5cm oily stain around the CPU thermal pad. This is the silicone compound that used to be inside the spongy material. How is this software related?
 

Odkrys

Senior Member
Your firmware is way out of date and a security risk to you. High temp issues do not exist with either Asus or Merlin for the AC86U now.
The high temperature problem of AC86U clearly exists in the 386 version, which shows a 6-7 degree higher temperature in idle state. (72c vs 78c on mine)

At low speeds, this is not a problem.
I am using 500Mbps symmetric internet service and the 2nd core went down after about 25 minutes of starting google drive download on 5Ghz wifi connection.

The 384.19 version maintains a maximum temperature of 95 degrees, and due to this 6-7 degree difference, the 386 version reached 100 degrees, causing a problem to bring down the core.

I've been using AC86U since 2017 and this is the first time I've had such a problem.

I am using AC86U in AP mode behind openwrt, so I will keep the 384 version.

Asus turned cpuwait back on on ac86u due to temperature issues, but I suspect that they turned off cpuwait and eee due to potential latency or disconnection issues in aimesh.

Personally I think Asus should clean up the GPL so that people can build firmware without aimesh or tm modules.
 

heysoundude

Part of the Furniture
Personally I think Asus should clean up the GPL so that people can build firmware without aimesh or tm modules.
If that should ever happen and you decide to fork, or if you learn how to do this without Asus needing to do anything, I hope you'll let us know.
 

bbunge

Part of the Furniture
AC86U overheating issues are hardware related, not software. It overheats because of the way it's made. CPU wait disabled on some Asuswrt versions just revealed the issue. AC1900P from 2017 also has the same hardware flaw like AC86U around the same production year - 2-3 years use at high temperatures makes the thick thermal transfer pad hard and dry. Older routers have 5cm oily stain around the CPU thermal pad. This is the silicone compound that used to be inside the spongy material. How is this software related?
AC86U in my garage at 30 C. Router CPU at 73.8 on firmware 3.0.0.4.386_44470. Garage will hit 38 C in the afternoon and I have never seen the AC86U go above 80 C. Does not have cooling fan installed.

No problems here with hardware or firmware.
 

gerardr

Regular Contributor
AC86U in my garage at 30 C. Router CPU at 73.8 on firmware 3.0.0.4.386_44470. Garage will hit 38 C in the afternoon and I have never seen the AC86U go above 80 C. Does not have cooling fan installed.

No problems here with hardware or firmware.
Is the router on a wire shelf (i.e. mostly open from underneath) or mounted in some other way? Thanks!
 

Tech9

Part of the Furniture
AC86U in my garage at 30 C. Router CPU at 73.8 on firmware 3.0.0.4.386_44470.

Your AC86U is not in Router mode. The CPU there does nothing. Show it to me in Router mode and 38C ambient, make a video.
 

FernandoF

Occasional Visitor
Here's my personal contribution, just as additional reference:
  • RT-AC86U manufactured in 2019, running in Router mode
  • No add-ons, no VPN, no ethernet connections, 2.4GHz radio at 20MHz, 5GHz at 40MHz (80MHz is not currently needed, resulting in 4-5C lower 5GHz temperature)
  • After upgrading from 384.19 to 386.3_0 (with several NVRAM/Factory resets, etc.), I observed a consistent CPU temperature increase of 6C
  • The router now idles at 48C above room temperature - that delta is very regular within an ambient temperature range of 17C to 24C
  • No change detected after the upgrade to 386.3_2 (also a "clean" install)
Thank you all.
 
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dh99999

Occasional Visitor
High temp issues do not exist with either Asus or Merlin for the AC86U now.

Ah, yes they do...

I and many others have demonstrated many times now that the issue is associated with the jump between 384 and 386 firmware versions - around 6-10 degrees hotter with 386, resulting in CPU core shutdowns when they hit 100 degrees.

You can probably rightly argue that the root cause is poor thermal management and the issue was always there with the AC86U, but the core shutdown did not occur in 384, hence the issue only causing issues with 386.

It also does not impact all AC86U users, but there are certainly many of us with the issue...
 

Hazel

Senior Member
Your AC86U is not in Router mode. The CPU there does nothing. Show it to me in Router mode and 38C ambient, make a video.
@bbunge s' 'garage'

IMG20190509145224.jpg
 

gk802

Occasional Visitor
RT-AC68U running in router mode with Samba and DLNA options active. CPU temp was 83-87 degC depending on the time of day and room temp. Added an AC Infinity 3 speed 120mm USB-powered fan (using separate power supply) with speed on the lowest setting, aimed at the rear of the router. The fan is effectively silent at this speed. CPU temp now 60-65 degC. Added a scheduled script that writes the CPU temp out to a log file on USB every 4 hours. I review the log periodically and do dust removal as needed.
 

Lynx

Senior Member
For use in your scripts. Just have the router push this out to a tannoy system:

 
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ArchDevil

Occasional Visitor
My AC86U got a temperature rise of 6-10c after connecting my NAS to it.
I have a fan blowing air at the back, before i connected the NAS temperatures was 72-74c now they are 79-84c.
Still better than 100c without the fan but yeah..
Gotta try that copper shim and thermalpad mod soon..
 

dogf

Occasional Visitor
Does the 386 merlin version temperature issue exist in all type of router? or just exists with AC86u?
 

glenw

New Around Here
AX86 running smoothly in terms of temperature. Thanks to Wiz & Pidy here for the info on how to monitor with SNMP and custom config files.

1630168998804.png
 

Hazel

Senior Member
Does the 386 merlin version temperature issue exist in all type of router? or just exists with AC86u?
In general, it mostly concerns the RT-AC86U. For the record: there have been issues, not in all RT-AC86U's but apparently in some series recent firmware updates did lead to higher temperatures and in other (mosty earlier series), it did not lead to any problems. The airflow construction of the RT-AC86U appears not to be ideal and ASUS cutting costs by using cheaper parts in later series hasn't helped either. This however does not mean that every RT-AC86U is affected. And in my personal experience, the situation has definitely improved with the more recent builds, temps have gradually settled down.
 
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