For a few years now, I’ve been using a Linksys E4200 v1 router (running DD-WRT) as the main router at my house. However, because the WiFi signal from the router isn’t strong enough to reliably reach all the rooms in the house, I picked up a few inexpensive Belkin F7D3302 / F7D7302 v1 Wireless N routers, flashed them with DD-WRT, and configured them as access points.

In exchange for their very low price (I picked them a couple years ago, refurbished, for around $20 each), there are a few drawbacks. First, they only broadcast on 2.4Ghz WiFi frequencies. Second, whoever designed their cooling should be taken out behind the tool shed at beaten with a stick; there’s a single vent, at the bottom of the unit, that does very little to cool these babies down.

Since these were long out of warranty, and so cheap to begin with anyway, I decided to undertake a project of trying to upgrade the cooling on one of these units enough to be able to safely overclock it (the E4200 units can be overclocked without any additional cooling).

Taking the Belkin Apart

To open the unit, locate and remove the small silver screws on the bottom. I had to cut through the label on bottom to find one of the screws:

Bottom screw locations

With the screws removed, you can remove the bottom stand and see the vents.. that would normally be OK, except that they “vent” down almost directly into that bottom stand!

Bottom “vents” exposed with the base removed.

Using a flat-head screwdriver or a multi-tool, pry open the corner near the power supply input:

I recommend opening the device here

Then slide the tool up toward the top of the unit as you gently pry outward:

Move carefully and slowly, and you’ll eventually get the top cover off.

You can see in this photo (with the top cover removed) where the tabs are that hold the cover in place. Once the cover is removed, locate the two main chips inside that say “Broadcom” on them:

The two chips that heat up are the ones marked “Broadcom.”

Prepping the Heat Sinks

Since I hadn’t spent a lot on these routers, I didn’t really feel like spending a lot of money on this modification. So I picked up some Cosmos VGA RAM cooling heatsinks on Amazon for $7. They come in a back of 8, which was perfect, since I had four routers to mod. I also purchased a small 3.5 gram tube of my favorite thermal compound: Artic Silver 5.

The perfect tools for making things cool

The Cosmos heat sinks come with adhesive, but I don’t trust them.

The heat sinks had their own adhesive, but I don’t roll like that.

The supplied adhesive can easily melt under too much heat, and since I was installing these heat sinks on a vertical surface, I didn’t want them to possibly slide off and short something out on the circuit board. So to make sure I’d have a clean surface for my thermal compound, I peeled off the adhesive and scraped off as much of the black stuff from the bottom of the heat sinks as possible:

My first pass at removing the supplied adhesive from the heat sinks.

I used some Goo Gone to remove the remaining adhesive (if you don’t have Goo Gone in a kitchen cabinet, you should get some right now), then used an alcohol swap to make sure the bottom of the heat sink was ready for the thermal compound:

Use Goo Gone and rubbing alcohol to prep the base of the heat sinks.

Installing the Heat Sinks

If you’ve never used thermal compound before, you really need to fight the urge to overdo it. This really is a case where less is more. Apply just enough to create a thin film of the compound on the bottom of the heat sink, then use something like a toothpick to spread it as evenly as possible out to the edges and corners. Press a heat sink onto the center of each of the two Broadcom chips, and hold them in place for a few seconds.

Heat sinks installed

Here’s a close-up of the installed heat sinks. It’s OK for a little bit of compound to ooze out from the edges of your heat sinks, but too much is a bad thing.

Close-up of the installed heat sinks.

Venting the Cover

Heat sinks aren’t much use unless there’s airflow across them to pull away heat, so I also drilled some holes in the top cover to help increase airflow inside the unit. I used a ruler to help draw four straight lines across the cover, then drilled holes along those lines… doing my best to “eyeball” them and space them evenly. If you do this mod, feel free to drill whatever pattern you like.

Drilling some quick and dirty vent holes.

With the holes drilled, I snapped the cover back into place and reattached the base:

All buttoned up!

Testing my Mod

To do a fair measurement of the effectiveness of this mod, I placed my modded unit next to an un-modded unit and connected it to the same network. I let them both sit for about 15 minutes, to make sure they both had a chance to come up to temperature:

Head to head: modded against unmodded.

After 15 minutes, the internal temperature of the un-modded router reported itself as 50.85 °C (123.6 °F). The modded router reported an internal temperature of 47.17 °C (120.5 °F).

To be honest, that wasn’t as big a difference as I’d hoped. I should say, however, that neither access point was that “busy” during the test. I tried connecting a few mobile devices to each and surfing the web, but those temps stayed pretty solid. A difference of only 3 °F was kind of disappointing, so I decided not to attempt overclocking the unit (yet?) until I can get the temperature down a few more degrees. The next step would be a fan mod, but that would bring the cost of a modded unit pretty darn close to a newer unit that’s vented properly, has more features, and can be overclocked right out of the box. If I figure out another approach that’s cost effective, I’ll do a progress update on this post.

So for now, I’m just running slightly cooled access points, and while I can’t quantify it, I’ll just tell myself that a cooler device is a happier device… and that maybe I’m getting just a smidge more WiFi reliability. 🙂

UPDATE: At the suggestion of another geek buddy, who astutely suggested that rising heat would want to escape upward rather than outward, I removed the cover and drilled an array of vent holes in the top of the router. My testing revealed that this got me a few more degrees cooler — after leaving both routers on all day, they’re now showing 52.6 °C (126.7 °F)  vs. 49.4 °C (120.9 °F). But that’s still not enough for me to feel comfortable overclocking these babies. Maybe a cheap fan is the answer?

Got questions, comments, or feedback? I welcome them below!