AX-86U operating temperature...

[Cr00zng]

My new Asus router CPUs run at high temperature:

That's about 155 degree in Fahrenheit, that rather high. Especially, when compared to my i5-3350P, also four cores:

For the Asus router with passive cooling, this might be normal, but I'd want to cool it off. Fan noise is an important consideration and the two of the Noctua NF-A8, 5V, PWM, with USB Power Adaptor Cable seemingly fit the requitement. Yes, I can modify the mounting to attach it to the router.

Is there any preferred solution that others use for this purpose?

TIA...

 

[kapekohicafe]

im using ax86u, mine is at 79c though im using merlin fw.

 

[Kendo]

70-71 C with the AC68U here. A silent cooler will surely help, good luck.

 

[bbunge]

71 C here. Still well within limits.
There are a lot of things to worry about in this world. Router temperature is not one of them.

 

[Cr00zng]

Thanks everyone...

My router does have the 386.2.2 Merlin firmware.

The CPU temperature of 70 Celsius is hot in my view, even for an SoC type of CPU. Utilizing thermal pad between the SoC and the heatsink, instead of the thermal compound like Artic Silver, probably contributes 10-15 degree Celsius to the SoC temperature, if not more. Not to mention that the thermal pad has the tendency to dry out and loosing some of its cooling efficiency on the long run.

Adding two 80mm, 5V Noctua fans with USB power adapter will improve cooling. If not, there's always the option to add copper shims and artic Silver thermal compound. Ideally, it would be nice bringing the temperature down to a more comfortable, low-40s temperature range. If my custom built full tower PC can run in the low 30's range, I cannot see why a router shouldn't be able to low-40s.

I worry about things, that I can control, anything beyond that, oh, well I'd love to...

 

[SoCalReviews]

You should expect the reported router CPU temperatures to vary since the ambient room temperature and humidity can also effect the router CPU temperature.

 

[RMerlin]

Especially, when compared to my i5-3350P, also four cores:

That's comparing apples with steak here... Absolutely nothing in common between the two.

 

[Cr00zng]

The SoC/CPU temperature also depends on the utilization of the router, in addition to the surrounding environment. The latter one will not change and the increased airflow provided by two fans will lower operating temperatures. The increased airflow on the otherhand may result in increased dust buildup, but will keep that in mind...

Yes, the only thing common between the router's CPU, rather SoC (BCM4908) and the desktop CPU is the four cores. Beyond that, there's not much common. This doesn't mean that the router's operating temperature around 70C is a OK, even if it is within Broadcom's specifications. Lowering this to ~50C would reesult in longer life and less operational issues in my view. The two Noctua fans should be here in couple of days and I'll post the operating temperature once the fans are installed.

 

[ColinTaylor]

Your particular router temperatures are perfectly fine, quite low in fact. This subject has been flogged to death, repeatedly, in multiple threads. Some people just can't accept it no matter how many times it's explained.

 

[1ceLaz0r]

Noiseless passive cooling is just fine even with my OCD

 

[Tech9]

My new Asus router CPUs run at high temperature:

It runs just fine. One router only has overheating issues and it's not AX86U model.

 

[Kendo]

Put a 12 cmm silent blue cooler in the back yesterday, it is not attached or mounted to the router, still "stole" 11 degress from the cpu, which is great imho.
This way the router also has a nice discrete dark blue glow from the back (at night).
Original temps were 50 - 53 - 71 C, now down to 46 - 49 - 60 C.
(I have the AC68U btw and did not want to lose the warranty).

 

[Cr00zng]

I didn't know, that this is such a touchy subject, that had been discussed to ad nauseam. Evidently, there are fans for both sides and I've pretty much placed myself on the side of the router is running too hot. While I respect others views on the subject, it didn't stop me from installing the already ordered, two 80mm Noctua fans, here are the results:

The ambient temperature had been 73 degree Fahrenheit with relative humidity of 45%.

The 25 degree Celsius (77F) temperature drop makes me more comfortable running this router. There's still room for improvement, but I think this will do for awhile...

Thanks everyone...

 

[SoCalReviews]

Theoretically cooler should be better but it's not an issue that seems to be a problem for most users. It's just a preference that some people want their routers to run cooler just because it makes them feel better but not because it improves anything. Maybe the router does last longer but we don't know. With the one exception being router overclocking I've never read about anyone measuring performance improvements either. Regardless... Thanks for posting that information. If someone else has an insatiable itch to cool their AX86U router we know it can be done.

Note: To avoid excessive dust buildup from the increased air flow running through the router you might want to look at using some kind of dust filter screen or simply slow the fan speed down a little (with resistors). You could also clean any dust buildup if it gets excessive. As you may know it is similar to dust buildup in PCs that have constant high speed air flow. The excess dust can block the heat sink and/or ventilation ducts and cause the computer to overheat. Besides less noise it's one reason they use passive cooling with oversized heat sinks and larger slower case fans on many of the high end PCs, servers, etc..

 

[Cr00zng]

Theoretically cooler should be better but it's not an issue that seems to be a problem for most users. It's just a preference that some people want their routers to run cooler just because it makes them feel better but not because it improves anything. Maybe the router does last longer but we don't know. With the one exception being router overclocking I've never read about anyone measuring performance improvements either. Regardless... Thanks for posting that information. If someone else has an insatiable itch to cool their AX86U router we know it can be done.

Note: To avoid excessive dust buildup from the increased air flow running through the router you might want to look at using some kind of dust filter screen or simply slow the fan speed down a little (with resistors). You could also clean any dust buildup if it gets excessive. As you may know it is similar to dust buildup in PCs that have constant high speed air flow. The excess dust can block the heat sink and/or ventilation ducts and cause the computer to overheat. Besides less noise it's one reason they use passive cooling with oversized heat sinks and larger slower case fans on many of the high end PCs, servers, etc..

I agree and it is certain, that the themal design of the AX-86U router is sufficient in most cases. Especially in my environment, where are 2-3 people with active connections at any given time. The longetivity may be a factor, but it is probably 5-6 years down the road. At which point, it'll be time for a new router anyway, mainly for Asus stops supporting the router. You are correct, it boils down to what people prefer and in my view, neither side is wrong.

Precaution had been taken to prevent dust buildup; this is the filter that suppose to arrive today:

Both of the fans are blowing air in the router, that had been the easiest to filter out dust.

I just didn't like the router's thermal design and the resulting "high" temperatures. I couldn't find a teardown for the AX-86U, other than the PCB layout for the CPU and the Wi-Fi chips. The AC-68U is a similar design and it's heatsink layout is added in the picture below:

The AX-86U probably has similar design, albeit the sizes are probably different. In either case, the two layers of thermal pad and heatsink aren't as efficient transferring heat as a single layer. Some people prefer to replace the second layer of the thermal pad with copper shims, better heat transfer efficiency, that results in around 15C CPU temperature drop. I don't disagree with them, it's just too much work adding the shim for me, even if it retains the passive cooling design.

Well, unless I go crazy and want to drop the CPU temperature around 30C, nah....

 

[SoCalReviews]

I agree and it is certain, that the themal design of the AX-86U router is sufficient in most cases. Especially in my environment, where are 2-3 people with active connections at any given time. The longetivity may be a factor, but it is probably 5-6 years down the road. At which point, it'll be time for a new router anyway, mainly for Asus stops supporting the router. You are correct, it boils down to what people prefer and in my view, neither side is wrong.


Well, unless I go crazy and want to drop the CPU temperature around 30C, nah....

Having the dust filter on the incoming air is good. That should help prevent internal buildup.

Coming from my past PC home build and mod days I get it. Please post some photos of your next water cooled or heat pipe cooled router mod project if and when you get around to it. Stay cool and be cool.

 

[Cr00zng]

Having the dust filter on the incoming air is good. That should help prevent internal buildup.

Coming from my past PC home build and mod days I get it. Please post some photos of your next water cooled or heat pipe cooled router mod project if and when you get around to it. Stay cool and be cool.

I still build PCs for family and friend, but never seen the the need for more than air cooling. As long as the CPU temperature stays within 15-20C above ambient temperature at idle, there's no need for water cooling in my view. Now, if you'd asking 20+ years ego, back in my overclocking days, the answer would had been different...

I still like mess with devices and looked in to the router further. One of the reason is the back cover for the AX-86U:

The label and the solid back behind it pretty much covers CPU, effectively limits the benefit of placing a fan above it. The AC-68U has a more suitable back for utilizing two fans for router cooling. The label is pretty much between the CPU and the two WiFi chips:

The partially blocked fan over the AX-86U CPU was reversed and check the router temperature:

Doing so actualy resulted in a modest CPU temperature increase, compared to the two fans blowing in posted yesterday. It made me curious, what would be the router CPU temperature with a single fan over the WiFi chips? Here's the result:

That's the best option for the AX-86U router with the 80mm Noctua fan. A 1C degree increase over two fans blowing in to the router just fine, no need to run two fans.

BTW... The fans are not connected to the router's USB port; they are connected to iPhone 6/8 AC chargers.

 

[Kendo]

^^ Will keep that in mind, thanks for sharing the info.

 

[scaramonga]

Shoved a Noctua 60mm fan on my AX-88U at top with a 3D printed duct designed specifically for it.

Pretty good, silent, in fact, you can't tell its running unless you look at it. Cut a little grill to fit in there also, to stop dust 73c was previous CPU temp.

 

[HTBruceM]

Shoved a Noctua 60mm fan on my AX-88U at top with a 3D printed duct designed specifically for it.
Cut a little grill to fit in there also, to stop dust

You can't get away with dropping that little bomb without showing us your 3d printed duct!