Router temperatures

mromero

Senior Member
yes, and even the slightest bit helps. I had wired a 120mm 12v fan to a usb plug and taped it on my 86U and got 66C temperatures. This last time, I just set it standing on its edge about 4 to 5 inches away, not "pointed" at the chip, just towards the router, and that got me the same 66C temps
So is blowing air into the Asus router better than extracting the excess heat?
 

heysoundude

Part of the Furniture
As a ham radio op and electronic guy for years Asus really needs to stop using thermal pads. These hefty processors need to be physically mounted to a metal heat sink with proper heat sink compound. This would end the massive over heat issues.
So is blowing air into the Asus router better than extracting the excess heat?

I agree with heatsinks.
fans are easy if you don't want to buy a router every few years; server rooms/datacenters are full of them for the same reason - to move air through equipment that generates heat in operation so it lasts as long as possible, and yes, bringing cool air in to carry heat away is the way to do it (rather than trying to exhaust the hot air, unless the hot air egress has been specifically designed for it)
remember what asus is in business to do: sell equipment. if they sell stuff that doesn't expire mechanically or technologically, they won't be in business too long.
 

bbunge

Part of the Furniture
AC86U as an AiMesh node running at 61.6 C. on 386.2 beta 1. No fan.
 

Kees17760

Regular Contributor
After reading several reports of higher temperatures I just checked mine and noticed that 386.2 beta 1 has also caused a temperature increase on my RT-AC86U. It is now 91 degrees celcius. I forgot what is was exactly, but after the release of 386.1 final it certainly went below 85 degrees and with 386.2 beta 1 it's hovering between 89 and 91 degrees Celcius. I really don't care, I'm not going to install active cooling as everything works perfectly fine (and I hate the idea of active coolers on the back on my beautiful routers) and I certainly don't want another temperature discussion, but if there's anything I can report on this beta, it's that the temperature on the RT-AC86U (all LAN ports in use) has risen indeed compared to 386.1 final. Now I must confess that I added one additional LAN-cable as an ethernet backhaul for my AIMESH node, but it seems unlikely that that causes a temperature increase of a minimum of 4-7 degrees celsius, as someone suggested.

Out of interest: Is there a way to check the temperature on my RT-AC68U AIMESH node?
"cat /sys/class/thermal/thermal_zone0/temp" divided by 1000

Perhaps add that to a script which runs every ten minutes or so and save the output to a file.
 
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gattaca

Senior Member
So is blowing air into the Asus router better than extracting the excess heat?
Affirmative. My own simple testing by running the same fan in both push/pressurize vs pull/exhaust modes with it strapped to the rear-side of the vertical standing ASUS AC86U and AX86U reported blowing air INTO the router's back-side (push/pressurize) lowered the reported operating temps of 2.4/5.0/ARM pCPU more than pulling air (pull/exhaust) through the model - at least for these oriented vertical models.

I've NOT tested the pull or push model on the horizontal models like the AC-88U. YMMV. Stay safe. Stay alive. Peace.
 
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elorimer

Very Senior Member
Okay, I get that this thread is separated out from the beta as just noise.

This thread is just about the 86U.

This thread is just about the changes some see in .2B, and I assume not because of anything to do with the Merlin beta, but perhaps something new in the GPL we are first seeing in the beta.

Maybe there is something Asus changed. In the .1 beta, these issues in the 86U led to the discovery that Asus had disabled the CPU_Wait setting, which Merlin then reverted for his fork.

Without that change, and with whatever was going on before, simple extrapolation suggests I would be CPU limited at 100C.

This could be my own 86U, or it could also be everything I've thrown on it, and most likely the latter. For an indeterminate period I am 4000 km from my router, so I can't explore whether, for example, this might be due to the implementation of cake in the beta vs the entware version, or the change in stock, or whether this would be improved without so many addons.
 

KingBravery

Senior Member
Affirmative. My own simple testing by running the same fan in both push/pressurize vs pull/exhaust modes with it strapped to the rear-side of the vertical standing ASUS AC86U and AX86U reported blowing air INTO the router's back-side (push/pressurize) lowered the reported operating temps of 2.4/5.0/ARM pCPU more than pulling air (pull/exhaust) through the model - at least for these oriented vertical models.

I've NOT tested the pull or push model on the horizontal models like the AC-88U. YMMV. Stay safe. Stay alive. Peace.
My ambient temp is almost 33C. I put 2 fan to blow the AX86U from front side and not the backside. My AX86U temps drops much from 75C to 56C. So the push method is better I think.

DSC_05136.jpg
 

Matthew Patrick

Senior Member
Affirmative. My own simple testing by running the same fan in both push/pressurize vs pull/exhaust modes with it strapped to the rear-side of the vertical standing ASUS AC86U and AX86U reported blowing air INTO the router's back-side (push/pressurize) lowered the reported operating temps of 2.4/5.0/ARM pCPU more than pulling air (pull/exhaust) through the model - at least for these oriented vertical models.

I've NOT tested the pull or push model on the horizontal models like the AC-88U. YMMV. Stay safe. Stay alive. Peace.
Nice findings!! My AC86U usually hovers around 70-80 at max when it was on 384.19 . Now it hovers at minimum, at 80C. Lol. And going up to 90C . Sometimes more when cpu load is high. It's definitely not optimal since it's ventilated and the room it's in is usually air conditioned ...

I heard about EEE making it much hotter, i usually just use 2 lan ports. One for my brothers laptop and one is for my 24/7 RaspberryPi.

So I bought a usb fan. Still shipping... It says it's supposed to be compatible with AC68U, and AC86U. Looks to be okay since it has this filter to filter dust. But idk if it's cleanable , so I guess I'll just set it and forget until about a year then I'll buy a new one since it's pretty cheap.
 

MvW

Senior Member
I can't believe what I've just done. All these years I've resisted with every new discussion about temperature but now I've given into it, as my temperature has risen to 94 degrees celcius. Ambient temperature is 20.9 degrees celcius.

I've just done what I swore I'd never do: I ordered 2 fans for my RT-AC86U on Amazon.nl. Or actually 4, because they had two types and no information on sound levels so I'll have to find out after arrival whether the sound levels are acceptable. I'm incredibly sensitive to sounds (which is real fun when being a single parent of a great 13-year old autistic kid with lots of (audible) tics, adhd and an anxiety disorder) and even the mechanical ventilation system of our apartment gives me the creepers at times because of the continous buzzing 15 hours a day. So please, let these fans, be silent.

This is what I ordered:
https://www.amazon.nl/gp/product/B08FYNF435/ - Set of 2*70 mm fans with dust covers
https://www.amazon.nl/gp/product/B08FML31NW/ - Set of 2*70mm fans without dust cover
https://www.amazon.nl/gp/product/B0748C1SJS/ Y-cable to split the USB port.

I need the splitter because the RT-AC86U (Main Node) also serves as a printer server for a (self-powered) Dymo Labelprinter 450 connected to the USB 2.0 port, which is used daily intensively for printing the pictograms (I don't even know if that's English, but those are icons, pictorial icons) for my kids planning board because communicating with the assistance of images is essential in his case. I hope this works and other wise I'll have to setup the AIMesh Node as a printer server. And the USB 3.0 port is in use for the USB stick with entware and all the other goodies.

Everything was in stock and I ordered before cut-off time so if all goes well, they should be here by tomorrow.

The only thing is: they're both blowing air out of the router, instead of in as described above. Now I guess I could reverse polarity or mount them the other way around if possible, but given the fact that they're going to create a different airflow anyway, I'll see if the results are sufficiently lowering the internal temperatures.
 
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MvW

Senior Member
First, you need to know the address. If you don't, look in your DHCP Leases and you can probably figure it out (mine in 192.168.81.41 for example). When I type that in to the browser, I get the login page for my AiMesh node. When I enter the name/pw it switches me over to my main router. So, I'm not sure if it is possible to get into GUI of node.

However, when I SSH (I use Xshell) and I put in the info, I can get a command line. So, if you know how to look up temp through command line (I don't) then I'd imaging that would work.

Maybe others can give you better info, but this might get you started.

@MvW

cat /proc/dmu/temperature

Connection established.
To escape to local shell, press 'Ctrl+Alt+]'.

[email protected]:/tmp/home/root# cat /proc/dmu/temperature
CPU temperature : 76

[email protected]:/tmp/home/root#

I just found out that I had to use the same public/private key combo as I use for the main router, so apparently that's copied to the AIMESH Node as well. I had no clue, but hey, it works.

Temperaturewise the RT-AC68U AIMESH Node has no issues, I guess:

Code:
ASUSWRT-Merlin RT-AC68U 386.2_beta1 Wed Mar 10 16:44:42 UTC 2021
[email protected]_WHITE-7130:/tmp/home/root#  cat /proc/dmu/temperature
CPU temperature : 68▒C

Ambient temperature is slightly lower, around 18 degrees Celcius. It's in one of the bedrooms. It's literally doing nothing, there's not even a mobile client connected to it. We live in a small L shaped ground floor apartment and the concrete walls and double glazing with some sort of coating in between the layers, cause the mobile clients to switch almost immediately to another when you walk (or drive) around the corner of the hallways towards the living room.
 

MvW

Senior Member
"cat /sys/class/thermal/thermal_zone0/temp" divided by 1000

Perhaps add that to a script which runs every ten minutes or so and save the output to a file.

That didn't work on my RT-AC68U:

Code:
[email protected]_WHITE-7130:/tmp/home/root# cat /sys/class/thermal/thermal_zone0/t
emp
cat: can't open '/sys/class/thermal/thermal_zone0/temp': No such file or directory

The command @JohnD5000 gave above, did give a a result: 68 degrees Celcius. Which seems acceptable to me. At least, even when it was my main router, it was always around a similar temperature level. Now it's just an AIMesh Node looking for something to do, so basically waiting for someone heading for the bedrooms.
 

AntonK

Very Senior Member
Nice findings!! My AC86U usually hovers around 70-80 at max when it was on 384.19 . Now it hovers at minimum, at 80C. Lol. And going up to 90C . Sometimes more when cpu load is high. It's definitely not optimal since it's ventilated and the room it's in is usually air conditioned ...

I heard about EEE making it much hotter, i usually just use 2 lan ports. One for my brothers laptop and one is for my 24/7 RaspberryPi.

So I bought a usb fan. Still shipping... It says it's supposed to be compatible with AC68U, and AC86U. Looks to be okay since it has this filter to filter dust. But idk if it's cleanable , so I guess I'll just set it and forget until about a year then I'll buy a new one since it's pretty cheap.
@gattaca and @Matthew Patrick do you have fans you can link to that are compatible with vertical-standing routers like the AC86U and the AX-86U (do these two have the same grilling/venting design on their backs)?

Thanks,
AntonK
 

bbunge

Part of the Furniture
Nice findings!! My AC86U usually hovers around 70-80 at max when it was on 384.19 . Now it hovers at minimum, at 80C. Lol. And going up to 90C . Sometimes more when cpu load is high. It's definitely not optimal since it's ventilated and the room it's in is usually air conditioned ...

I heard about EEE making it much hotter, i usually just use 2 lan ports. One for my brothers laptop and one is for my 24/7 RaspberryPi.

So I bought a usb fan. Still shipping... It says it's supposed to be compatible with AC68U, and AC86U. Looks to be okay since it has this filter to filter dust. But idk if it's cleanable , so I guess I'll just set it and forget until about a year then I'll buy a new one since it's pretty cheap.
I bought the fan designed for the AC68U/AC86U.Had a thin piece of foam stuck to the fan for a filter which I removed. Used the fan for a month.
Fans so blow or suck more air which brings in more dust which requires more maintenance. With a fan with a filter the filter gets blocked the router heats up and bam, no more router.
Linksys WRT1900AC and similar family members have a cooling fan, which never runs. So, is the fan worth it?

My AC86U mesh node under load runs at 62C in a 20C room with no fan. Cooling fan, that is. I'm still a fan of Asus routers!
 
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MvW

Senior Member
@gattaca and @Matthew Patrick do you have fans you can link to that are compatible with vertical-standing routers like the AC86U and the AX-86U (do these two have the same grilling/venting design on their backs)?

Thanks,
AntonK

I just linked two of them a few posts back: https://www.snbforums.com/threads/router-temperatures.71123/post-672869. These are suitable for RT-AC68U, RT-AC86U and others. If you Google 'fan' and 'router' there will be several similar results. Remarkable to see that there are several kits sold specifically for ASUS routers...
 

bbunge

Part of the Furniture
@gattaca and @Matthew Patrick do you have fans you can link to that are compatible with vertical-standing routers like the AC86U and the AX-86U (do these two have the same grilling/venting design on their backs)?

Thanks,
AntonK
https://www.amazon.com/your-orders/...es=&returnUnitMappingId=&shipmentId=DBdvy4cwv

You shouldn't need a fan for the AX86U. The above may work with duct tape but the seller advises to not use the USB3 port to power it. The AX86U only has USB3 ports.

Forget the fans. with current firmware heat will not kill your router.
 

WillyTP

Regular Contributor
I really don't undestand how there can be such big differences in temps among AC86U owners.
Even without fans, some people have normal temperaturs, others extremely high.

Any ideas?
 

Tech9

Part of the Furniture
Hey guys, I hope everyone is okay during the challenging times.

I run electronics recycling business on the side and I repair electronics as a hobby. Component level repairs from PC motherboards to iPhones. I have my small lab with what's needed for my fun projects. A few resurrected RT-AC86U routers are sitting on my shelf. Those fail in big numbers. Asus is reusing parts from previous models and they don't fit properly. Some of you may have noticed a number of huge thermal transfer pads. The gaps between the ICs and the heatsink are as large as 3mm. It's built as cheap as possible with hope for the best. There are many thermal stress points on this PCB. It lights up like NYC night lights on the thermal camera image. Lead free solder doesn't like thermal stress points. VRMs fail as well as RF ICs. I had to replace few VRMs and reflow a RF IC to bring a few back to life. The repair is not worth it. Fix one thing and something else fails. The bad design always wins. Using copper shims and thermal paste drops the temperatures you report by 20C. A fan on top drops it further another 20C. My general recommendation is to avoid this model. If you already have it avoid on/off cycles to reduce the thermal stress. A fan is a workaround temporary solution. When the VRMs fail you get one LAN port light lit or some other LED half lit. When the RF IC fails you get Channel 0 in your UI. I don't know why Asus uses 19V PS and then drops the voltages down with multiple VRMs. It only creates more failure points and generates more heat. Other routers do fine with 6-12V PS. I can't find schematics online for Asus routers. Looking at the components used nothing needs 19V. Good luck to RT-AC86U owners.
 

AntonK

Very Senior Member

elorimer

Very Senior Member
I don't know why Asus uses 19V PS and then drops the voltages down with multiple VRMs.
I think habit, honestly. I've had two laptops and four routers that all used the same brick.
Forget the fans. with current firmware heat will not kill your router.
Not worried about killing the router, even though it killed my 87U (a worse design). I'm thinking more about the thermal limiting that kicks in.
And the USB 3.0 port is in use for the USB stick with entware and all the other goodies.
I avoid the USB3 port for sticks. I think the higher current and speed available on these are bad, particularly for little plastic ones. But I think the 12v fans operating at 5v only draw around 50ma, so almost nothing.
 

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