$9 Router Cooling (RT-AC68U Example)

I just started with this ROM, and have similar temps to report 55/57 wifi, and 81 CPU.

Is there a correlation between turning on/off certain features and temp? I've been trying that and I can't find changes that are material. Turing off CTF lowers CPU about a degree.

paulbates said:

I just started with this ROM, and have similar temps to report 55/57 wifi, and 81 CPU.

Is there a correlation between turning on/off certain features and temp? I've been trying that and I can't find changes that are material. Turing off CTF lowers CPU about a degree.

Click to expand...

You'll see in my post I was getting the same temperature (80degC) with zero percent activity in core one and core 2. So I see that as the 'resting' temperature. But as I was unaware of the temperatures until this topic came up - and as I've never had any problems of any sort - I'm pushing it to the back of my mind.

martinr said:

You'll see in my post I was getting the same temperature (80degC) with zero percent activity in core one and core 2. So I see that as the 'resting' temperature. But as I was unaware of the temperatures until this topic came up - and as I've never had any problems of any sort - I'm pushing it to the back of my mind.

Click to expand...

Yes, I saw that. That advice makes sense. With my CPUs' activity near the floor as well, I have to believe the out of the box firmware is experiencing about the same. I tested this on an HDX movie from Vudu over wifi to my TV. For the last 15 minutes, its streaming at 12mb, and CPU1 is bouncing between 3% and 8%, CPU2 between 1% and 3%. The cpu has gone up 2 degrees and the wifi about 2 as well... I have traffic monitor and all of the toys turned on.

All to your point, time to move on to other things. Like transferring some $$ to Merlin. This firmware is a very special piece of software.

Thank you

Paul

On the subject of laptop coolers, not all of these blow air up. Some suck it down and out the sides. That reverses the intended passive flow and seems to me to be something to be avoided.

I personally used this: http://www.amazon.de/Tischventilator-Geschwindigkeiten-geräuscharm-Aus-Schalter-schwengbar/dp/B00L9HGJQ2

When we had real high ambient temperatures here...

Had 10C drop on Low and 25C drop in High on CPU and radio temperatures, and it is barely audible even on High...

It is always preferable to blow air out not in. In the case of the AC87U the coolar needs to blow air out from below because there is nowhere that air can escape anywhere else quickly enough.

While stock CPu temperatures at 80C or above may seem fine but a year down the road the router will start to fail from the build up of heat causing damage to the other components on the board that are only designed to operate up to 60C. A lot of passively cooled systems with a very small CPU (such as switches) are designed to operate up to a 50C environment because the board itself uses a lot of standard chips and components. When heat builds up those components end up running at higher than normal temperatures and eventually fail (similar to running a CPU at 100C all the time. Stable but will break down soon)

Think of it as ASUS trying to get you to buy a new router every year or 2.

I was hoping to whip the back (or front) off my RT-AC68U and quickly take some spot temperature measurements so there's something factual to go off. However, I can't see any obvious way (eg screws) to separate the two halves; can't say I'm surprised with such a sleek-looking design. If it can it be opened up without damage, I'd give it a go; if not, I'm leaving well alone.

Not sure if this would help. Mine doesn't have the rubber feet, therefore no torqx screws. Guessing the same trick with the credit card works to get it apart.

paulbates said:

Not sure if this would help. Mine doesn't have the rubber feet, therefore no torqx screws. Guessing the same trick with the credit card works to get it apart.

Click to expand...

Thanks, Paul. It's kind of you to send that info. The RT-AC68U lacks the rubber feet (as you say), so no hidden screws. So, I'm not going to attempt to prize the 2 halves apart. This is one where "if it ain't broke, don't fix it" applies, especially as I disturbed a connection and temporarily lost Internet access merely by moving the router.

I see from a posting back in Ocyober 2013, that RMerlin''s had his RT-AC56U apart multiple times, but it looks as if the number one design requirement for the RT- AC68U was to prevent its being opened up.

I'm leaving well alone!

@martinr - The AC68U has two Phillips head screws under the label in the center/back of the router. There are a LOT of clips that need to be disengaged around the front panel (work slowly with a credit card or plastic disassembly tool).

Just wanted to add to this as I'm running the HGG Merlin Fork on my AC87U right now and enjoying the options to increase transmission power but didn't want to push it too far until I got some cooling sorted out.
Therefore (and after reading this thread) I went and grabbed this:
http://www.ebay.co.uk/itm/281067042733?_trksid=p2057872.m2749.l2649&ssPageName=STRK:MEBIDX:IT

Considering it was so cheap I expected rubbish and figured the fans would be crap and at least I can use the perspex plate to mount some good quiet fans on that I can get elsewhere.

It arrived today and I thought I'd give it a try as is and have so far been pleasantly surprised.
The AC87U fits on it perfectly and the usb power cable I just plugged straight into the USB2 socket at the bak of the AC87U and USB plug itself has a male and a female end, so you can still plug in something like a printer.

As for the temps I'm running said firmware with both the 2.4 GHz and the 5GHz running at 75% which really strengthens signal and coverage for me and when I first plugged this cooler in my temps were as below


but within half an hour they were down to
2.4 GHz: 45°C - 5 GHz: 56°C - CPU: 77°C
which is quite a big deal for something I was going to just buy for parts!

Anyway, I want to try this firmware at 100% on both and see how this handles (remember that o% on this fork is greater power than 100% on the regular Merlin) but was thinking on a slight mod first.

Someone on this thread raised concern re all that cold air (and dust) being forced in with no place to escape, so I was considering reversing one of the fans (maybe the middle one) to pull instead of push, so the 2 at the side are blowing in cold air while the centre one is sucking out the hot.

Given there are a lot of ventilation notches all over the bottom of the AC87U and the cooler's fans are attached with screws it could be pretty easy and worth trying.

Anyone got any thoughts on this? Would it make a difference which fan I changed in relation to the positioning of (for example) the cpu?

So a question and a cool result from a cheap ebay purchase!

northwinds said:

Anyone got any thoughts on this? Would it make a difference which fan I changed in relation to the positioning of (for example) the cpu?

Click to expand...

What is that device to the immediate left of the router? (not the Alias DVD set) - might want to move that away from the 87U...

And FWIW - might also consider moving those DVD's away from the router - all sorts of metalized plastic disks in close proximity...

Just ordered one. At £3.74 with free postage, I thought it would be shipped from China, but no, it's from London. (Internal postage must eat most of the £3.74.)

An interesting experiment would be to see if taking the usb power take-off from a separate source has any effect on internal temperature.

I will also look at placing, ahead of the air intake, a thin sponge filter - the type that are used in vacuum cleaners (availabe on ebay) or cooker-hood extractor filter paper. I used to use the latter on my previous laptop, whose cooling fan had a grille on the underside, held on with a couple of screws. I'd cut a small circle and trap it behind the grille and change it every month or so (sometimes, when the output air felt warmer than it should be!). It was very effective: the fan blades stayed pristine, but the filter paper always showed a build up of grey dust - dead skin cells. And the output air flow felt, with a fresh paper, just as strong as without it.

And even if the fans achieve little, the lovely blue light will complement the blue LEDs on my ASUS router and make it the centrepiece of the room, as indeed it should be!

northwinds said:

Someone on this thread raised concern re all that cold air (and dust) being forced in with no place to escape, so I was considering reversing one of the fans (maybe the middle one) to pull instead of push, so the 2 at the side are blowing in cold air while the centre one is sucking out the hot.

Given there are a lot of ventilation notches all over the bottom of the AC87U and the cooler's fans are attached with screws it could be pretty easy and worth trying.

Anyone got any thoughts on this? Would it make a difference which fan I changed in relation to the positioning of (for example) the cpu?

Click to expand...

My 87U is a refurb so maybe it is different. I have a set of cooling slots on the bottom right and side right, where the CPU is, and on the bottom left and side left where the 2.4g radio is. No slots in the bottom middle where the quantenna chip is. Then a line of slots along the back top edge above the connections. It sits on a 17" laptop cooler blowing up, but neither usb port will spin it up so I draw from another device. I have maybe 20 devices connected at a time on a gigabit network, just a couple wireless devices, and only a 25mps internet connection, so I don't think I'm taxing the router. My temps are 40/41/60.

If I understand the internals, there are three large heatsinks on the top of the circuit board, so passively cooled air must be intended to draw in from the bottom and sides, around the circuit board, over the heatsinks and out the top back. If yours is like mine, a center fan won't be here or there. If you have center vents, then I don't think you want it pulling air out, because you will stifle the airflow around the board and over the heatsinks. I don't think you want the side fans pulling air out either, because the flow will be from the sides and down. I think positive pressure, with some lost to the sides, is the only way to go.

Update:
I have since added an adjustable power supply for my fan (see top of thread) and lowered the fan voltage from 12v to 3v while still retaining the lower temps. So it seems the router doesn't require a lot of airflow to reduce the temps dramatically.

Thanks for that!
That was what I was wondering.

I've gone and updated to the latest beta of the HGG Merlin Fork - 378.55.4 - so I could try out the new "Enhanced Mode" on "Maximum Coverage" for my 2.4GHz and have set the output power for both to 100% and temperatures have hardly changed at all!

elorimer said:

My 87U is a refurb so maybe it is different. I have a set of cooling slots on the bottom right and side right, where the CPU is, and on the bottom left and side left where the 2.4g radio is. No slots in the bottom middle where the quantenna chip is. Then a line of slots along the back top edge above the connections. It sits on a 17" laptop cooler blowing up, but neither usb port will spin it up so I draw from another device. I have maybe 20 devices connected at a time on a gigabit network, just a couple wireless devices, and only a 25mps internet connection, so I don't think I'm taxing the router. My temps are 40/41/60.

If I understand the internals, there are three large heatsinks on the top of the circuit board, so passively cooled air must be intended to draw in from the bottom and sides, around the circuit board, over the heatsinks and out the top back. If yours is like mine, a center fan won't be here or there. If you have center vents, then I don't think you want it pulling air out, because you will stifle the airflow around the board and over the heatsinks. I don't think you want the side fans pulling air out either, because the flow will be from the sides and down. I think positive pressure, with some lost to the sides, is the only way to go.

Click to expand...

Thanks for that!
The device is my Virgin Media Superhub which I have feeding the signal to the AC87U (on modem mode) - do you think I should move it?

Re moving the discs is a difficult one as I'm in a small flat in London and running out of space.... :-/

sfx2000 said:

What is that device to the immediate left of the router? (not the Alias DVD set) - might want to move that away from the 87U...

And FWIW - might also consider moving those DVD's away from the router - all sorts of metalized plastic disks in close proximity...

Click to expand...

Hope it works well for you too!
Cheers!

martinr said:

Just ordered one. At £3.74 with free postage, I thought it would be shipped from China, but no, it's from London. (Internal postage must eat most of the £3.74.)

An interesting experiment would be to see if taking the usb power take-off from a separate source has any effect on internal temperature.

I will also look at placing, ahead of the air intake, a thin sponge filter - the type that are used in vacuum cleaners (availabe on ebay) or cooker-hood extractor filter paper. I used to use the latter on my previous laptop, whose cooling fan had a grille on the underside, held on with a couple of screws. I'd cut a small circle and trap it behind the grille and change it every month or so (sometimes, when the output air felt warmer than it should be!). It was very effective: the fan blades stayed pristine, but the filter paper always showed a build up of grey dust - dead skin cells. And the output air flow felt, with a fresh paper, just as strong as without it.

And even if the fans achieve little, the lovely blue light will complement the blue LEDs on my ASUS router and make it the centrepiece of the room, as indeed it should be!

Click to expand...

northwinds said:

Thanks for that!
The device is my Virgin Media Superhub which I have feeding the signal to the AC87U (on modem mode) - do you think I should move it?

Re moving the discs is a difficult one as I'm in a small flat in London and running out of space.... :-/

Click to expand...

Well nudging around a thinga a bit might help... don't need to be much, just a bit..

Ole Geiser said:

Cooler Master SickleFlow 120mm (Amazon)
Before:
2.4 GHz - 5 GHz - CPU
50 °C - 57 °C - 80 °C
After:
38 °C - 46 °C - 52 °C
View attachment 4409

View attachment 4410

Click to expand...

Is it blowing air in or sucking it out of the router?