Router temperatures

[MvW]

Turning on EEE (pwr config --eee on) via script does help, but only a little.

Are there any (known) downsides to turning EEE back on?

 

[Wade Coxon]

Are there any (known) downsides to turning EEE back on?

None that I have encountered.

It was on by default before 386.1.

 

[Jack Yaz]

None that I have encountered.

It was on by default before 386.1.

I'd suspect its in Aimesh 2.0 if any issues do exist

 

[Amwjujo]

I was fallowing this temp conversation across the forum since 386.1 when my AC86U went up from 64C to 94C.
This seems to be specific to this model, as my other 2 AC68U are running nice and cool.
I bought a kit of 2 cheep china fans. The temperature dropped to 54C but the fans are so noisy ....
I just hope that sharing ideas here someone might figure a way how to fix this.
Best.

 

[Tech9]

I bought a kit of 2 cheep china fans. The temperature dropped to 54C but the fans are so noisy ....
I just hope that sharing ideas here someone might figure a way how to fix this.

12V fans running on 5V is the simplest way to reduce the noise.

 

[Tech9]

I'm truly thankful for all the options that have been provided, but I have become disabled over the past years

There are many products on the market with design flaws, Marco. Look around how many AC1200 class home routers are offered with 100Mbps ports at the back. I don't know why they exist. Change the fans to 12V version and run them on 5V to reduce the noise levels when you have the chance and focus on more important things in your life. If you have the space for horizontal router the other option is a laptop cooling pad. The router will work just fine in horizontal position.

 

[SomeWhereOverTheRainBow]

12V fans running on 5V is the simplest way to reduce the noise.

Talking about some hot cables there. So much resistance.

 

[goodwin_c]

So, this is how it is looking - with mount, that I've posted few pages earlier:

This is with the fan running on the lowest possible speed (connected to main 19V line with DIY adapter from male and female barrels, with experimentally found resistance to start fan on power-on and keep low RPM), and replaced thermal pads with copper shims + good thermal grease

 

[elorimer]

Talking about some hot cables there. So much resistance.

That's not how Ohm's law works, is it? If a 12v device draws 1 amp at 12v, it will only draw 5/12 of an amp if you feed it 5v. Or 2 watts vs 12 watts.

Now putting 12v into a 5v fan, yup, you're gonna be burning down the house.

right, sure, but if taking the front off - or making some holes in it - drops the temp significantly as well as passively, it makes more sense to me to do so.
Surely you can agree that any drop in temperature will make most people paying attention to and aware of/concerned with temperatures less concerned about shortening the lifespan of their (main) router.

I was too brief. If I understand it, the board for the 86U is mounted so that all the components are facing the back of the router, and there is nothing on the front side. All the cooling is from the vents on the back, starting just above the ethernet plugs, exiting the strip of vents across the back of the top. I don't think holes in the front are going to increase air flow appreciably by going around the board to the other side. But the slightest wisp of air into the back side does wonders.

If you have the space for horizontal router the other option is a laptop cooling pad. The router will work just fine in horizontal position.

I have thought about this. The problem is the WAN/LAN cables are in the way if you lay it on its back, and then the external antennas don't point the way you want. Better to cant the laptop cooling pad.

 

[gattaca]

^^^ Summary or options! Thanks for all the great posts, ideas and examples!!
I'm modifying my post with my current recommendations after testing several fans, in varying positions of the router either vertical (as designed) or horizontal as appears later in this thread.

1. Easiest solution - ignore the heat and hope for the best + plan on buying a new router every few years. If the ambient is really warm, expect the thermal throttling to engage. Throttling will deliver erratic performance.
2. Obtain one of the several 120MM fans IDed below and position them on the REAR blowing INTO the rear of the router. NOT Exhausting. I've run several tests and the delta is 5-8C depending on the fan.
3. Check out the Noctua 5V fans and compare the dBA ratings. Smaller fans spin faster and generally deliver more NOISE. I've never used a 40MM fan but I think @Tech9 said that works fine too.
4. Activate all the "green" power saving options in a boot script - will deliver lower temps but not the lowest latencies or absolute best performance. Note: These /bin/pwr options vary by router model! The AX86U has several others options vs the AC86U and they are not always the same.
5. When selecting a fan you will be in the room with, always pay attention to the noise levels (dBA) ratings. Multiple fans are cumulative.
6. Always pay attention to the power draws when you plan to connect any device to a USB port. Stay under 0.5A / 500mA MAXIMUM at 5VDC from any USB port!

I've decided:

1. I'm not performing router surgery as long as the fan can keep the temps stable. I am not seeing some of the issues being reported. I have always added fans to my routers as the noise remains barely audible for me in my locations.
2. I might purchase one of these AC Infinity double-ball bearing fans on my next Amazon order and give it a try. If it is really 18dBA + they run 50K hours + 5V + we can slow them down with the control AND still move the air, then that might be simplest OOB and the quietest option I've seen thusfar.
3. I ordered a Noctua NF-P12-redux-1300 (12V) and a USB to Fan cable. This solution yielded the quietest and most effective cooling solution I've seen when the fan is positioned on the rear, blowing into the router. THIS 12V model fan WILL spin up at 5V. So that gives you the option of using a USB port or providing a smaller 12V USB PSU and ULA adapter to slow the 12V fan down. You can also use the Noctua-NF-P12-redux-700 (I've not tested for starting up at 5V)...but there's a pretty good chance that will be PERFECT with a 12VDC PSU. )

FAN Summary (last updated 20 Mar 2021)

1. 5V Noctua options (These will be louder than using a 12V fan slowed down with the USB port or external 12VDC PSU)
   1. 40MM - NF-A4x20 5V - 14.9 dBA/9.4 m3H (tiny volume of air)
   2. 80MM - NF-A8 5V - 17.7 dBA / 55.3 m3H
   3. 60MM - NF-A6x25 5V - 19.3 dBA/29.2 m3H
   4. 120MM - NF-A12x25 5V - 21.4 dBA / 96.2 m3H
   5. 120MM - NF-F12 5V - 22.4 dBA / 93.4 m3H
   6. 92MM - NF-A9 5V - 22.8 dBA / 78.9 m3H
2. ULN 12V options are exceptionally quiet!! (I think I'll try a NF-S12B with a small 12 PSU (on hand) and this will be as quiet as you can likely achieve with a fan!!) This looks like the quiet winner!
3. These units will deliver a very quiet solution using a 12VDC FAN + 12VDC PSU.
   1. NOTE: These fan models below will NOT spin up at 5VDC as I've tested two of them!! If you want then, use them with the little Cooler Guys 12V PSU further below!
   2. >>>>> 120MM - NF-S12B redux-700 - 6.8 dBA / 56.9 m3H <<<<<< lowest dBA and will be the quietest I've found so far in their specs while still delivering good air volumes.
   3. 120MM - NF-S12A ULN - 8.6 dBA / 74.3 m3H
   4. 120MM - NF-A12x25 ULN - 7.6 dBA/ 39.4 m3H with ULA
4. 12V 120MM Redux -1300 or 900 or the original NF-P12 with the LNA or ULA
   1. BLUF >>>>>>> THIS FAN IS the MOST flexible I have found WRT effective + quiet! <<<<<<<<<
   2. It will be nearly SILENT with the ultra-low-noise adapter (ULA) or low-noise-adapater (LNA) installed or spin up to a good clip without them. This is from my direct testing.
   3. The "Redux" models are essentially 'bare-fans' They do not come with the various mounting hardware or ULA or LNA cables. It is a bare fan at a lower price. You have to have or buy those parts extra.
   4. If you want those parts, then buy the original Noctua NF-P12 FLX 120MM/12V on Amazon. This is the link. They still have these available -> https://www.amazon.com/dp/B000YSONMO/?tag=snbforums-20
   5. The "Pxx" series was very popular when released.
   6. The "Pxx" fans will spin up with low-startup voltages. Many other Noctua (and other fans) will NOT spin up at 5V!!! So do not assume any 12V fan will spin up unless you test it or it's published in the specs.
   7. NF-P12 redux-1300
   8. This seems to be the closest non-REDUX model with all the accessories -> Noctua NF-P12 Flx
   9. I've tested this "cooler guys" little fan PSU, seem perfect if you want to a separate 12V PSU for your 12V fans.
      1. CoolerGuys 12VDC tiny fan PSU
   10. Warning - DO NOT CONNECT 5V fans to 12V PSU or it will destroy them!
   11. BTW, the GENUINE BOSE 12V PSU S024EM1200180 are very good and well designed 12 1.8A power-supplies. I've found them often for less than $15 USD on eBay. YMMV. Example --> https://www.ebay.com/itm/GENUINE-BO...203960?hash=item548fd2b638:g:TUAAAOSw2Upfud6~

Modified 17/18 Mar 21 - Adding this great page which let's you sort by noise dBA. I used quietpc a while back and had forgotten about this page.. --> https://www.quietpc.com/noctuafans

The NF-S12 series are the quietest but I'm not sure they will handle the static pressure, so you will need to try. I also do not know if they will spin up on 5V...but they would turn even slower there so might not be enough air.

I have an older NF-P14 (discontinued) but check the REDUX versions which is 140mm and it spins up nicely on 5V.. and does well cooling the AC88 for years - virtually silent.

Good thread, great ideas. I never knew people had so many concerns or issues with cooling these routers. I doubt ASUS will change their manufacturing methods - so it's up to us to improvise as required. Stay safe, stay alive. Peace.

 

[Matthew Patrick]

Anyways, later when I use fans, if it's always in the low 50s. Are there any benefits in disabling all those power saving features that are now enabled by default? Like cpu wait etc?

 

[dscline]

That's not how Ohm's law works, is it? If a 12v device draws 1 amp at 12v, it will only draw 5/12 of an amp if you feed it 5v. Or 2 watts vs 12 watts.

Ohm's law isn't even directly applicable here, as motors are inductive devices, not resistive. All other things being equal (load), the speed of a DC motor is directly related to the applied voltage (and current relates to torque). Fan laws tell us that the power required by a fan changes with the cube of the fan speed. So running the fan at 5v will significantly reduce the power consumed by the fan. I'm not sure, but I think @SomeWhereOverTheRainBow 's comment may have been related to the concept of reducing voltage from 12v to 5v via a resistor? But that's not the case if you're simply pulling 5v from a 5v supply (such as USB power). That's where the 5v suggestion typically comes from, as 5v power is readily available in PCs, or anything with USB.

 

[maxbraketorque]

I note in your Hack/mod thread that you have used a 3mm copper shim for the CPU.

To me, this would be the ideal fix, as it resolves the underlying issue with the standard heat-sink solution, and isn't a potentially noisy band-aid by adding a fan. I'm also skeptical that adding additional passive ventilation holes will provide any benefit at all.

...

My takeaway from some of Tech9's earlier posts is that a fan is the best solution for the average AC86U because it provides cooling for all the heat generating components which preserves caps and apparently helps reduce the potential for solder cracking.

However, for routers such as yours where the CPU or one of the radios readily overheats or becomes really hot without a fan, that issue should also be addressed.

 

[Sky1111]

^^^ Summary or options! Thanks for all the great posts, ideas and examples!!

1. Easiest solution - ignore the heat and hope for the best + plan on buying a new router every few years. If the ambient is really warm, expect the thermal throttling to kick in and create erratic performance.
2. Obtain one of the several 40-120MM fans IDed here and run it blowing at the rear of the router. IMHO, a single AC Infinity 120MM fan with the separate PSU / controller affords maximum flexibility and lowest risk. If their dBA specs are right, will be about as quiet as you can get with a 120MM fan and can be quieter with the speed controls!
3. Check out the Noctua 5V fans and compare the dBA ratings if you want the quietest possible solution. Smaller fans tend to spin faster so look at their dBA grids and find the one with the smallest dBA ratings. I've never used a 40MM fan but I think @Tech9 said that works fine too...
4. Activate all the "green" power saving options in a boot script - will deliver lower temps but not the lowest latencies or absolute best performance. Note: These /bin/pwr options vary by router model! The AX86U has serveral others options vs the AC86U and they are not always the same.
5. When selecting a fan you will be in the room with, always pay attention to the noise levels (dBA) ratings. Multiple fans are cumulative.
6. Always pay attention to the power draws when you plan to connect any device to a USB port. Stay under 0.5A / 500mA MAXIMUM at 5VDC from any USB port!

I've decided:

1. I'm not performing router surgery as long as the fan can keep the temps stable. I don't have some of the issues being listed here as I've always added fans as the noise remains barely audible for me in my locations.
2. I might purchase one of these AC Infinity double-ball bearing fans on my next Amazon order and give it a try. If it is really 18dBA + they run 50K hours + 5V + we can slow them down with the control AND still move the air, then that might be simplest OOB and the quietest option I've seen thusfar.
3. I might try a smaller 5V or quieter 12V. I'll update my post with the quietness in order / ranking:. Need to check the current use which you have to open each page.. (May update later)
4. 5V Noctua options -->
   1. 40MM - NF-A4x20 5V - 14.9 dBA/09.4 m3H (tiny volume of air)
   2. 80MM - NF-A8 5V - 17.7 dBA / 55.3 m3H
   3. 60MM - NF-A6x25 5V - 19.3 dBA/29.2 m3H
   4. 120MM - NF-A12x25 5V - 21.4 dBA / 96.2 m3H
   5. 120MM - NF-F12 5V - 22.4 dBA / 93.4 m3H
   6. 92MM - NF-A9 5V - 22.8 dBA / 78.9 m3H
5. ULN 12V options I just noticed are (these look really viable now to me and very quiet)
   1. 120MM - NF-S12B redux-700 - 6.8 dBA / 56.9 m3H
   2. 120MM - NF-S12A ULN - 8.6 dbA / 74.3 m3H

Good thread, great ideas. I never knew people had so many issues with cooling these routers. I doubt the makers will change their manufacturing methods... so it's up to us to improvise as required. Stay safe, stay alive. Peace.

thanks for the summary!

• I concur on not performing router surgery - I usually sell my routers after few years, and whatever money I recover, helps to pay for the next toy. Although I should admit - I am very tempted! Very long time ago I did a surgery on a crappy Dlink router - added heatsinks on all chips, cut a hole in the cover and added 80mm fan - that dramatically improved the stability of that POS
• Size of the fan: I suggest 120mm, and the reasons are:
  • Unless you cutting a "cold air intake" hole in the router cover, the aiflow from the fan will be fighting with tiny holes of the cover. Larger the surface, more holes (by the way, same concept is used in newer high efficiency hourse furnace air filters - the filters are now 5inch, not like older 1inch standard filters)
  • Generally speaking, 120mm needs lower RPM to push the same amount of air as smaller fan (strictly comparing the same design of blades)
• Fellow Canadians: one good option for a fan would be Noctua NF-P12 redux-1700 PWM, High Performance Cooling Fan, 4-Pin, 1700 RPM - that's less than CAD$18
  • (now I am thinking - maybe I should replace fans on my desktop with these? LOL)

 

[dlandiss]

That's not how Ohm's law works, is it? If a 12v device draws 1 amp at 12v, it will only draw 5/12 of an amp if you feed it 5v. Or 2 watts vs 12 watts.

There will be some reduction in current, but not proportional as the motors are not pure resistors. Back EMF changes the equation.

 

[SomeWhereOverTheRainBow]

12V fans running on 5V is the simplest way to reduce the noise.

Talking about some hot cables there. Soon much resistance

Ohm's law isn't even directly applicable here, as motors are inductive devices, not resistive. All other things being equal (load), the speed of a DC motor is directly related to the applied voltage (and current relates to torque). Fan laws tell us that the power required by a fan changes with the cube of the fan speed. So running the fan at 5v will significantly reduce the power consumed by the fan. I'm not sure, but I think @SomeWhereOverTheRainBow 's comment may have been related to the concept of reducing voltage from 12v to 5v via a resistor? But that's not the case if you're simply pulling 5v from a 5v supply (such as USB power). That's where the 5v suggestion typically comes from, as 5v power is readily available in PCs, or anything with USB.

it applies if the fan is going to attempt to Draw more than allowed( potentially frying transistors or a usb port). The resistor would weaken the draw, but also produce a lot of heat via the resistor.. But this relies more on judging ampres than volts.

 

[Wade Coxon]

Talking about some hot cables there. Soon much resistance

it applies if the fan is going to attempt to Draw more than allowed( potentially frying transistors or a usb port). The resistor would weaken the draw, but also produce a lot of heat via the resistor.. But this relies more on judging ampres than volts.

That's still not quite how Ohm's law works.

Remember that W = I^2 x R

Adding resistance will increase power linearly, but the resultant drop in current will reduce power by the square of the current. Adding resistance to a fixed voltage circuit ultimately reduces the power and heat generation because the current falls.

Similarly, lowering the voltage drops the current (into a purely resistive load) and thus the power and heat.

 

[dscline]

Talking about some hot cables there. Soon much resistance

it applies if the fan is going to attempt to Draw more than allowed( potentially frying transistors or a usb port). The resistor would weaken the draw, but also produce a lot of heat via the resistor.. But this relies more on judging ampres than volts.

You have to be mindful of where you're pulling power from, but USB should have ample power. A 12v fan should theoretically run @ 41.67% of its speed when run @ 5v. The power requirements drop with the cube of speed change, or 7.23% of its 12v power. A 12v 200ma fan should draw about 14.5ma @ 5v. A USB port should be good for 500ma. Amp draw will be higher as it's starting up, but not THAT much higher. Besides, being a port that can have a wide range of things plugged in to it, cables that can short, etc., USB should have overcurrent protection. But if it's a concern, use an external power supply. Either way, you'll draw less power from a 5v power supply than a 12v power supply reduced with a resistor.

 

[Tech9]

Talking about some hot cables there.

No hot cables. The fan is not going to attempt anything. The most common cheap fans have a simple pulse generator rotating magnetic fields created by small coils under the fan core. The rotor has a ferro magnetic ring and follows the magnetic field. Reducing the power supply voltage reduces the power draw, magnetic field strength and possibly the frequency of the generator depending on how it's made. As a result the rotor turns with lower RPMs. If you have the equipment test it and see what happens. It's perfectly safe to use but I still don't recommend powering the fans off network gear USB ports. The reason is unknown type of fans different folks will buy and use. A fan for $5 on Amazon is manufactured in China for 50 cents with corresponding 50 cents quality. If you want to go the proper way Noctua, Corsair, Cooler Master etc. with fan controller is a better and longer lasting option.

 

[Deleted member 62525]

I was fallowing this temp conversation across the forum since 386.1 when my AC86U went up from 64C to 94C.
This seems to be specific to this model, as my other 2 AC68U are running nice and cool.
I bought a kit of 2 cheep china fans. The temperature dropped to 54C but the fans are so noisy ....
I just hope that sharing ideas here someone might figure a way how to fix this.
Best.

I have the same router for 2 years now. Running stand alone with Skynet, Unbound DNS and VPN. Never had issue with temps at all. It may as well be related to AiMesh.