Help: DIY CPU Fan w/ Potentiometer

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Yourrid
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Help: DIY CPU Fan w/ Potentiometer

Full disclosure: you guys know more about electronics and electricity in general than I can ever hope to understand, so I figured BLF would be a good source of info (read: trying not to burn my house down).

So I’ve figured out that my internet router has a serious problem with heat. Usual web browsing gets it warm, but playing online games (PS4) generates a serious amount of heat. As the heat increases, the bandwidth slows to a crawl. I can usually get ~40Mbps on 2.4GHz band at the start, but after about 30-45min, it slows to <1Mbps, which makes my “man cave” inhospitable. So after diagnoising the issue, I found my router was very hot (150F just on the exterior case). Let it cool down, back up to 40Mbps. Rinse, and repeat.
(ASUS RT-AC53U)

The router is just over a year old (out of warranty, but emailed ASUS asking WTF just in case) so I’d rather not spend another $100 on an even newer one. So I decided to try and solve the problem myself. I put a little 18650 clip on fan in front of the router, and it works great! The router stays cool, and the internet stays consistently fast. Here is the problem: the fan is outrageously loud. So I’m wanting to build a DIY cooling pad for it using some ball bearing case fans from my local MicroCenter.

Problems I’m running into that maybe you guys can shed some light on for me:

  • I prefer to hook this up to a USB wall outlet, which means I’m working with 5v. Most case fans are 12v. But they do sell some smaller 5v fans.
  • I’m considering using one of these USB Step Up Boost Module DC 5V to 12V Power Supply but am unsure about how safe it would be running it off of a standard cell phone wall charger.
  • I want to install a potentiometer so I can choose how fast/loud I want the fan to run, but I’m unsure as to which Watt and Ohm to purchase for a little 5v, less than 1Amp setup.

I’d appreciate any insight that you guys have. Thanks! Beer

Edited by: Yourrid on 10/17/2016 - 15:18
ImA4Wheelr
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Not an electronics expert here.  Just a thought.  Some of your existing 12v fans on hand may run at 5v.  The output will be less, but I take it you don't need much airflow.  Plus, slow is quieter.

everydaysurvivalgear
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Laptop fan would be the easiest way to fix this. You can try and add some extra heat sinking? Does the router get dusty?
This is expensive but you can get cheaper fans. Just put this under the router. I am not sure what would be getting hot? Does the router have an internal power supply?
Ll https://www.amazon.com/Antec-Notebook-Cooler-USB-Powered/dp/B0000BVYTV

Yourrid
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ImA4Wheelr, I’ve been researching this 12v to 5v idea as well. As far as I can see, some fans will work with 5v, but very slow. Some fans can’t even get spinning at 5v, so it just burns up the motor. I think 5v with a variable amperage would be the safest bet. But I was thinking the same thing initially.

everydaysurvivalgear, I found an old laptop cooling pad and have the router sitting on top of it now. Seems to work so far. The pad comes with 2 settings so I may tear it down and just upgrade the fan to a super quiet one. It doesn’t get dusty, and the power supply is external. I’m not sure why it seems to be getting as hot as it does either. I’m going to wait for ASUS to email me back before I open it up and take a look. I’m sure opening it will void the warranty, so I want to make sure Asus won’t take a look at it.

everydaysurvivalgear
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It could have an internal antenna to go along with the external antennas and they would be generating heat.

Kepling
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Like ImA4Wheelr said, most computer case fans will run fine at 5v.

Some brand names that make good quiet fans are:
Noctua, Thermalright, Scythe, Be Quiet!, Noiseblocker, Antec, Enermax.

Check out www.silentpcreview.com and their forum in particular.

tommachine12
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The ASUS RT-AC53 is suitable for very different internet users. Beer I bought ASUS RT-AC53 because i need an dual-band Wi-Fi 802.11 ac router. Wink Connected devices must be 802.11ac-compatible for good results. Here`s look a good examples jonsguideFlat Stare

Jinx
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Just buy one of these and stick it in the USB port on the router, safe, quite and easy!

USB fan

mdeni
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Put something like this, so every time the temperature reaches ~36 degrees it will turn on the fan, and when it drops to ~34 it will turn it off.

http://www.ebay.com/itm/Temperature-Switch-Control-Sensor-Thermal-Thermo...

djburkes
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A guy modded his Asus router . Yours is a different model but they may be laid out close to the same.

JamesB
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I have had a lot of USB fans and nothing comes close in my experience to the artic breeze in silence/CFM , the version with a foot and potentiometer is fantastic.

Joshk
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I had the exact same problem with my Asus RT-AC66U, which looks the same because it basically is the same. I ignored the issue and it eventually ruined it. When it was new it always rebooted after a hot crash. Later it only rebooted 1 out of 2 times after a hot crash. Eventually it only booted 1 out of every 50 restarts. That’s when I replaced it. You need to do whatever it takes to cool it off. The heat is messing it up.

chops728
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I’ve used 12v fans for tube audio gear—just find a wal wart power supply between 9-12v then add resistors to get the desired speed you want—Artic Cooling fans are the quietest—bigger fans can run a lot slower moving more air 120mm

Joshk
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I hear incredible things about this fan for $20:
Noctua 120mm Cooling Fan NF-S12A ULN

It says 43CFM at 8.6 dBA!

maukka
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JamesB wrote:
I have had a lot of USB fans and nothing comes close in my experience to the artic breeze in silence/CFM , the version with a foot and potentiometer is fantastic.

I’m also using this to cool the flashlights when doing runtime tests.

Yourrid
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I ended up buying a fan and usb controller through coolerguys.com. While I was waiting to receive my order, I ended up taking the cable router, and connected it directly to my PS4. Worked like a charm. I have a spare (2 year old) Asus router so what I did was connected the modem to the older router, connected the PS4 to the router, and then used the newer Asus router as a repeater downstairs.

Everything has been working flawlessly. Apparently routers use a heck of a lot more power when wireless rather than being directly connected via ethernet cable.

I appreciate everyone’s help. Seems like I was going about solving the problem the wrong way. I’m sure I’ll find use for the fan eventually Beer

Joshk
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Yourrid wrote:
Apparently routers use a heck of a lot more power when wireless rather than being directly connected via ethernet cable.

Yep. And way faster using the cable too.