Tuesday, October 2, 2018

Heat dissipating solution for Asus RT-AC86U router with USB cooling fans

The Asus RT-AC86U wireless router has a stand-up design and its heat management is relying on passive cooling.

Unlike those flatbed routers which we can easily provide heat dissipating solution to them by using normal laptop USB cooling fans, the temperature management solution for this stand-up router needs some tweaking to attach external fans to it. Luckily, there is ready made solution in the market, and it is quite cheap too.

If you are using AsusWRT-Merlin firmware in the router, you are able to read the runtime temperature reported at its Broadcom BCM4709 processor (CPU), Broadcom BCM4365E 2.4GHz WiFi SoC chipset and Broadcom BCM4366E 5GHz WiFi SoC chipset respectively.

In normal operation, the temperature at 2.4GHz WiFi chipset stays around 50-55 degree Celsius and the temperature at 5GHz WiFi chipset stays around 55-60 degree Celsius. However, the dual-core CPU temperature is always on the high side, staying above 70 degree Celsius, and there are users reporting that it can go up to above 90 degree Celsius.

If you are feeling uncomfortable with these kind of temperature readings and would like to lower them down to a more comfortable level, you just need to install a pair of external USB cooling fans at the back of the router.

The two 7cm fans are powered by 5V DC from the USB 2.0 port of the router itself. You can also plug it to the router's USB 3.0 port, but that port is normally used by external storage, USB Internet dongle, etc.

It is attached to the back of the router using 3M double-sided tape provided in the cooling fans set package.

Within 20 minutes, the pair of fans are able to cool down about 5 degree Celsius to both the 2.4GHz and 5GHz chipsets respectively. They can effectively cool down the temperature of the CPU by a whopping 20 degree Celsius.

With this heat dissipating solution, now the temperature at the 2.4GHz chipset reduced to around 45 degree Celsius, and the temperature at the 5GHz chipset reduced to around 52 degree Celsius. The CPU temperature greatly reduced to around 53 degree Celsius.

If I power down the fans by unplugging it from the router's USB port, all the 3 temperature readings will gradually increase, and went back to the previous high level within 20 minutes.

The fans are rotating at relatively low speed at 2100 RPM, making them pretty quiet. You can hardly hear their noise unless putting your ear very close to them during silent night.

According to their specifications, their noise level is at 18 dBA only. Their lifespan is around 50,000 hours, which is equivalent to over 2000 days, long enough to serve for the entire lifespan of the router.

Other than Asus RT-AC86U, this pair of USB cooling fans can also be used for Asus RT-AC68U router as both of them are having very identical size and casing build.


edge2002 said... Reply To This Comment

Hi would like to check with you, if I would like to make use of the current unifi turbo speed upgrade, means I need to purchase a TV box which support gigabit LAN port? is that so? or just connect a CAT6 cable to my current TV box LAN port would do?? thanks

Voyager8 said... Reply To This Comment


There are 2 devices that need to have gigabit network ports:

1. The broadband termination unit that connects to the fibre optic link. This device is provided by TM. If it is of old model with 100Mbps output port, you can call TM to come and replace with a new one with gigabit output port.

2. Your router that connects to the broadband termination unit using its WAN port and to your internal network using WiFi or its LAN ports. All its ports need to be gigabit, and its WiFi needs to support Wireless-AC in order to get the best from UniFi turbo speed. You will need to get a new one if it does not support gigabit and Wireless-AC.

The TV box can remain the same. The router's gigabit LAN port is backward compatible and can connect to 100Mbps TV box port. The speed for that particular port will be at max 100Mbps and will not affect the speed of the other gigabit ports.

edge2002 said... Reply To This Comment

thanks for your prompt reply
I had check my termination unit is huawei-HG8240W but could not find the WAN port support gigabit or not, do u have any idea?
seems could not locate any info from google too

edge2002 said... Reply To This Comment

if the TV box port still run at 100Mbps means the streaming speed will not improve even unifi had upgrade to Turbo Speed? is that so?

Voyager8 said... Reply To This Comment


100Mbps is good enough for 8k video streaming, 50Mbps is good enough for 4k video streaming.

Therefore, the TV video quality will not be affected.

You will know your termination unit is gigabit if your Internet speed can go above 100Mbps after Turbo. If your Internet speed unable to go above 100Mbps after Turbo, the port is very likely not gigabit, provided your router is already supporting gigabit.

Maelstrom said... Reply To This Comment

Hi. How do you install the fan? Air going in or air going out?

Voyager8 said... Reply To This Comment


Air is going in.

The fan axial at the center has 2 sides, one side is fixed and the other side moves when the fan rotates. Therefore, you can only attach the fan to the router by applying the double-sided tape on the non-moving side of its axial.

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