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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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