UPDATE: Newer versions of the DD-WRT firmware now include a web-based option for selecting your overclock speed, if it’s supported on your device. You can still follow these steps to overclock (and I recommend you continue reading so you understand what you’re doing), but now you can access overlocking on the Administration/Management tab.

Overclocking means forcing a device’s CPU to run at a faster clock speed than was set by the manufacturer. Overclocking is not for the casual user. The idea is that with a faster clock speed, a CPU can process instructions at a faster rate, providing a faster overall experience when using the device. The cost of overclocking, however, is increased heat. And heat is the mortal enemy of all electronics.

The Cisco/Linksys E4200 (version 1) router has a Broadcom BCM4716 CPU, which runs at a default clock speed of 480MHz. I’ve been able to reliably overclock it to 532 MHz, and I’m sure there are some crazies out there who’ve pushed it even further.

However, before I proceed with explaining how to overlock a Linksys E4200 v1 router, I need to make something crystal clear: overclocking is dangerous. If you mistype any part of the overclocking commands below, you can brick your router. If you choose an overclock value that is incompatible with your hardware, you can brick your router. Overclocking will increase the heat inside your router, and can potentially melt stuff, and can brick your router. If anything goes wrong, you can brick your router. Bottom line? Don’t do this unless you can live with the risk of possibly bricking your router.

These instructions are only for the E4200 v1, as different clock speeds are compatible with different units. I haven’t tested overclocking on any other routers. I don’t know what overclock settings will work with other routers, so please don’t ask.

I will not answer any overclocking questions in the comments below or via email. Please allow me to repeat that.

I will not answer any overclocking questions in the comments or via email.

Feel free to comment below with a “Yay! It worked!” or “Crap! I bricked my router, but I’m not mad at you, Steve, because you totally warned me and I have nobody to blame but myself!” or even share other tips or input. But unlike my other blog posts, if an overclocking question appears in the comments below, I’ll either ignore it or reply “See above.” If I get an email question related to overclocking a router, I’ll simply delete it without replying. There will be no exceptions. I’m not trying to be a jerk, I’m just trying to clearly state that you are 100% on your own if you proceed.

The very brief blurb on the DD-WRT overclocking wiki page says:

OVERCLOCKING CAN BRICK OR PHYSICALY DESTROY YOUR ROUTER! USING THE DD-WRT OVERCLOCKING FEATURE IS AT YOUR OWN RISK! WE GIVE NO SUPPORT ON IT OR ON BRICKED AND DAMAGED ROUTERS!

Have I scared you off yet? OK, if not, then I’ll admit that the three E4200 routers I have overclocked @ 532 MHz (they normally run @ 480 MHz) are running great. That’s not a huge clock speed increase, so I’m pretty comfortable with it. I haven’t noticed any temperature issues, but that doesn’t mean you won’t. I haven’t noticed any reliability issues, but that also doesn’t mean that you won’t. Again, if you choose to type the following lines to overclock your E4200, you do so at your own risk.

First, you’ll need to have DD-WRT running on your E4200. Follow these instructions to flash DD-WRT on your router, if you haven’t already done so. Although, if you’re not already running DD-WRT or some other third-party firmware on your router, you should probably ask yourself if overclocking is really for you. I’d recommend experimenting with hacked firmware first, before moving on to this more advanced stuff.

Now for the risky part. SSH in to your router (if you don’t know how to do this, stop now… you really shouldn’t be overclocking).

Once in the shell, type the following three commands to overclock the E4200 v1’s Broadcom BCM4716 CPU @ 532MHz:

nvram set clkfreq=532,266,133
nvram commit
reboot

Cross your fingers and pray while your router reboots. If it comes back from the reboot, party on! Check the CPU section of the Status:Router tab to verify that your CPU Clock value reads “532 Mhz.” If so, welcome to the Overclock Club. 🙂

If the router doesn’t come back from the reboot, I’m sorry. You have my sympathy. Try a hard reset of your router before you panic. Beyond that, I really can’t help you. Google, the DD-WRT forums, and the search term “serial cable” are your friends. Good luck.

Checking Your Temps

As I said before, heat is the sworn enemy of electronics, so if you’re overclocking, it’s a good idea to keep an eye on the temperatures inside your E4200. The following commands will return the temperatures of your respective wireless antennas. You can paste these on the command line in the shell, or in the Commands window of the GUI.

(Temps are now also available in the Status/Router GUI tab on newer firmware versions.)

For eth1 (2.5GHz antenna) temperature in Celsius:

echo eth1=$((`wl -i eth1 phy_tempsense|awk {' print $1 '}`/2+20))C

For eth2 (5GHz antenna) temperature in Celsius:

echo eth2=$((`wl -i eth2 phy_tempsense|awk {' print $1 '}`/2+20))C

If you want to display in Fahrenheit, you’ll need a two-line command to do the additional converstion:

For eth1 (2.5GHz antenna) temperature in Fahrenheit:

eth1=$((`wl -i eth1 phy_tempsense|awk {' print $1 '}`/2+20))
echo $((eth1*9/5+32))F

For eth2 (5GHz antenna) temperature in Fahrenheit:

eth2=$((`wl -i eth2 phy_tempsense|awk {' print $1 '}`/2+20))
echo $((eth2*9/5+32))F

Going Back to Stock

Even if the overclock was successful, you may have a reason return to the original clock speed for some reason. Maybe your router is overheating and you want to change things back until you can figure out a way to cool it better. Or maybe you want to revert to the original clock speed for some baseline benchmarks. Or MAYBE YOU JUST CAN’T HANDLE THE SPEED, BABY! Whatever your reasons, by examining the command you used above to overclock to 532 MHz, you may notice something mathematically interesting about the three numbers we used. See it? (Hint: if you can divide by 2, you’re “half-way” there… har, har.)

So, if you can remember the default clock speed for this router as mentioned in the 2nd paragraph of this post (fine… I’ll save you the scroll up — it’s 480 MHz), and doing some simple math, you can probably guess the command that will put things back to normal. Take the stock clock speed of 480, cut it in half (240), then cut that in half again (120) and you’re ready to go. Type this from the terminal:

nvram set clkfreq=480,240,120
nvram commit
reboot

As before, cross your fingers and think positive thoughts while your router reboots. After it comes back from the reboot, check the CPU section of the Status:Router tab to verify that your CPU Clock value is back to “480 Mhz.” Enjoy your slower clock speed! 🙂