CPU frequency scaling on the RT-AC68U

[goncalossilva]

Hello!

I've recently purchased an RT-AC68U and I'm rocking asuswrt-merlin on it (latest version).

The reported CPU temperature is always around 85ºC. This worries me a bit... It's winter here, I can't imagine what will happen in the summer I've noticed both CPUs are always clocked at 800MHz, all the time. At least that's what it seems.

Is it possible to change the cpu frequency scaling to "ondemand" somehow? I think that would help considerably in lowering these temperatures.

Thanks!

 

[RMerlin]

Hello!

I've recently purchased an RT-AC68U and I'm rocking asuswrt-merlin on it (latest version).

The reported CPU temperature is always around 85ºC. This worries me a bit... It's winter here, I can't imagine what will happen in the summer I've noticed both CPUs are always clocked at 800MHz, all the time. At least that's what it seems.

Is it possible to change the cpu frequency scaling to "ondemand" somehow? I think that would help considerably in lowering these temperatures.

Thanks!

I don't think this CPU supports frequency scaling, or at least it's not part of Broadcom's API.

 

[goncalossilva]

That's a shame

To others who also have the RT-AC68U: which temperatures do you generally see?

Mine's sitting at 87°C right now.

 

[wifi_reef]

Merlin 39 - about 4 hrs running - CPU@1200 / RAM@800

___________________WL0___/WL1____/CPU
Current Temperatures: 54 °C - 55 °C - 76 °C


air temp. 23 °C

Those are my normal temperatures and they jump few °C up when air temp goes to 27 °C - like 56 / 56 / 78

 

[goncalossilva]

I don't think this CPU supports frequency scaling, or at least it's not part of Broadcom's API.

I think it does. The reason is that this CPU was used 2 years ago on an Asus tablet (the TF101), and by default it worked on an ondemand basis.

Are there any instructions on how to build the asuswrt-merlin firmware? The "performance" mode is probably hard-coded somewhere, I'd like to try to switching it to "ondemand".

 

[goncalossilva]

Merlin 39 - about 4 hrs running - CPU@1200 / RAM@800

___________________WL0___/WL1____/CPU
Current Temperatures: 54 °C - 55 °C - 76 °C


air temp. 23 °C

Those are my normal temperatures and they jump few °C up when air temp goes to 27 °C - like 56 / 56 / 78

Wow, you OC and have much lower temperatures than I do, and air temperature is around 20ºC here. Maybe there's some defect in my CPU cooler, as my WL temperatures are similar (52ºC - 55ºC).

 

[wifi_reef]

nothing special indeed:

nvram set clkfreq=1200,800
nvram commit && reboot

that is all.

Router is standing backside close to the wall. There is a 10 cm gap between the wall and the unit's back. It is standing on the cupboard which has about 3 cm gap between the wall and the back.

 

[goncalossilva]

Hum, I'm starting to think I should swap mine. It's out in the open, no OC, and high temperatures.

Thanks for the details!

 

[RMerlin]

I think it does. The reason is that this CPU was used 2 years ago on an Asus tablet (the TF101), and by default it worked on an ondemand basis.

The TF101 used a Tegra2 CPU, while this router uses a BCM4708. Completely different chip, not even the same manufacturer (nVidia versus Broadcom).

 

[goncalossilva]

The TF101 used a Tegra2 CPU, while this router uses a BCM4708. Completely different chip, not even the same manufacturer (nVidia versus Broadcom).

You're right, my bad. Somehow I misread it while Googling for this

 

[clayhans]

Fix?

Hello!

I've recently purchased an RT-AC68U and I'm rocking asuswrt-merlin on it (latest version).

The reported CPU temperature is always around 85ºC. This worries me a bit... It's winter here, I can't imagine what will happen in the summer I've noticed both CPUs are always clocked at 800MHz, all the time. At least that's what it seems.

Is it possible to change the cpu frequency scaling to "ondemand" somehow? I think that would help considerably in lowering these temperatures.

Thanks!

I solved the temperature “problem” by putting this little fan (Thermaltake Mobilefan II 80mm External USB Case Fan) behind my AC68U router. My cpu temp is 66C not 87C. I know it is a hardware solution and not a firmware fix.

 

[goncalossilva]

I solved the temperature “problem” by putting this little fan (Thermaltake Mobilefan II 80mm External USB Case Fan) behind my AC68U router. My cpu temp is 66C not 87C. I know it is a hardware solution and not a firmware fix.

What kind of temperatures were you getting before this?

 

[Ford Prefect]

FWiW, I just purchased the AC68U a week ago and have seen 68ºC with stock and Merlin .38_2 FW.
Since yesterday, I moved to Merlin .39 and temps have just "jumped" to 71ºC, while I haven't changed anything in set-up or physical config.