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Posts Tagged Linksys

Cooling the Linksys E3000 – Part 2 – Inside the box

After much discussion and feedback regarding my original post “Cooling the Linksys E3000“, and my own curiosity as to why this router got so hot, I decided to press on and look further into it.

I’ve heard rumors that speculate that one of the reasons this router gets so hot is because of an underpowered AC/DC adapter. I generally don’t agree with that and here’s why: The device is hot but the adapter isn’t. In my experience AC/DC adapters which are under-powered will run the adapter hot — as it’s overloaded — and the device won’t function under load, as there’s not enough power to all of the components. In this case, the AC/DC adapter isn’t hardly warm (I just checked mine) and appears to meet the device requirements (12VDC 2A). So I don’t believe the heat issues are related to the adapter. So if the problem isn’t related to the AC/DC adapter, it must be due to lack of adequate cooling. I removed my cooling fan and opened the case. The screws are T10 torx security screws, labeled CR-VT10 in my kit, for the interested. The first thing I noticed after opening the router was that there was plenty of RF shielding and actually a heatsink mounted on one chipset. I decided against removing it as I didn’t have anything to replace it with if the adhesive didn’t re-stick. I then set up a moderate test to keep the router busy while I probed the uncovered chips with an infrared thermometer.
Here is my setup:

Wired:

  • Port 1: Wii streaming Netflix
  • Port 2: Gigabit NAS

Wireless:

  • 5Ghz Wireless-N device (300Mb/s) copying a large amount of data from the NAS

As you can see I’m far from pushing the router to it’s limits but I am certainly keeping it moderately busy. I ran this level of network activity for about 5 minutes then started taking temps. I found two chips that had operational temperatures above 45C:

The first was the Broadcom BCM4322KFBG controller at 62.8C

bcm4322kfbg

This is a product of the Broadcom BCM4322 family of 802.11n controllers. Here’s the datasheet.

The second was the Winbond W9751G6JB-3 DRAM chip at 47.6C. This is a 512Mb DDR2 SDRAM chip.

w9751g6jb-3

It seems to me now that the Broadcom chips are almost solely responsible for much of the overheating issues in this router family, with the DRAM chip potentially taking some of the blame as well. I’m planning on ordering a set of Zalman VGA heatsinks and put one of them on each of these chips. It should help a lot, especially with the fan on the bottom to keep the air moving.

As the nature of heatsinks is to transfer the heat from the chipset to the air, I’m sure that I’ll notice a slight increase in the temperature of the router’s case itself, but the resulting heat transfer should be improved with the aid of the fan, and I’m sure I’ll be able to expect my router to live a much longer life.

If anyone has any thoughts to share on this please do so in the comments below. Thank you!

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Cooling the Linksys E3000

A short time back I was shopping around for a new router. After some comparison shopping I decided on the Linksys E3000. (UPDATE: Read more on this at Cooling the Linksys E3000 – Part 2 – Inside the box)

However, I was having issues with my Wii randomly dropping off the wireless network. I started troubleshooting and accidentally happened on something that bothered me: This router got HOT. By hot I mean I checked it with my infrared thermometer and I got a reading of 61C from the bottom of the router. That’s well above it’s operational temperature rating of 40C.

First, a note on my configuration:

  • DD-WRT v24-sp2 (12/19/10) big (e2k-e3k)
  • 2.4ghz  and 5ghz access points, both in use
  • A single gigabit device on the wired lan.

I had a good deal of network activity going at the time, so I took most of the devices off the network, powered off the router for about 5 minutes, turned it back in and checked again. No measurable difference in temperature after about a  minute of operation.

My concern was that the router was simply too hot to continue operating like this. I was afraid of chipset failure.

I started in on a mod idea, with a couple of points:

  • The router needed to be cooled quietly
  • The router needed to be cooled in a way that wouldn’t void the warranty in case I ended up RMAing it.

I initially thought of driving a fan from the DC-in connector, but the barrel shape made it difficult to come up with a clean mod, and at 12 volts, it could get a little noisier than I wanted it to be. I wasn’t using the USB port, and that’s an easy 5v supply to a fan, clean and easy.

So I started with a simple USB-to-fan cable. Pulling the 5v supply off the USB port and to a fan connector was easy, and after a quick check with the multimeter said it was good to go. It worked great, but I found out that unfortunately none of the fans I had lying around ran at 5v; they were all 12v fans. I would have to buy a fan for this.

I figured a 120mm fan would give me good air flow at a low noise rate, along with covering most of the bottom of the router. A quick search turned up a Coolerguys 120mm USB fan. A 5v fan with a USB connector to boot. Oh well, I still get to keep my cable for another project :)

So I ordered the fan. It arrived quickly (not quickly enough, I was impatient! ;) ), and I started in on making it look nice.

Removing the grill from the fan was the first step, and it came off easily with a #2 Philips screwdriver.

I had some adhesive foam feet lying around from something else, and cutting them in half and stacking three gave me a nice fit with the finished feet measuring 25x20x28mm.

I added some 4mm rubber feet to the bottom of the fan to give it intake room, and test fitted it. It couldn’t have worked out better. The fan fit neatly under the router and ran quietly — I could barely hear it even when the room was completely quiet. The 4mm rubber feet allowed enough intake room under the fan, even though the fan could have easily moved more air with more of an intake space.

The result? A reading of 30CThat’s a 31C drop in surface temperature! Of course, if you do this, make sure the fan is blowing up into the bottom of the router; not down.

The Wii? As it turns out, it was in a spot where it got terrible signal to begin with. A wired adapter fixed it’s issue.

My thought at the end of this was “Why didn’t Linksys consider something like this from the beginning?” followed by “How soon until our home networking equipment has to be fan cooled?

Here’s all the photos from the mod project:

Have a Linksys E3000? Have your own cooling mod idea to share? Please feel free to share your thoughts in the comments below!

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