I’m curious to hear from anyone who is running overclocked rb532 boards (in particular at 333MHz) and if they’ve had in stability issues with them? I haven’t really seen any complaints at all with doing this, but have not run any production boards at this speed yet. Anyone care to post their experiences?
actually it is recommended to run them at 333Mhz. that does not cause any problems at all.
but why default frequency of routerboard 5xx series cpu is 264 MHz?
because it is it’s actual frequency. but as far as everyone has tested, it doesn’t hurt to run it at 333mhz. no problems whatsoever
No problem running about 60 RB’s with 333Mhz 
Regards
What is the official procedure to switch the default frequency to 330/333? Mine always reverts back to 264/266.
Thanks,
Dave
From de routerboard manual:
Changing CPU Frequency
By default, the RouterBOARD 500 series boards are equipped with 266MHz processors, which may be
overclocked to 333MHz with a varying degree of success (no guarantees). The boards that are tested to
work on 400MHz must be especially ordered, and our ability to provide them, as well as schedule depends
on the demand for this factory option.
The bootloader is made so that you must first try a different frequency before it could be set permanently,
and if you do not apply a frequency permanently, it would fall back to the previous setting on the next power
cycle. It is still possible, however, that the board is not working properly on the frequency you’ve applied, so
the default (266MHz) CPU frequency can be restored. To do that, power the board with the S1 button
pressed, then unplug the power, and when you will turn the board on again, it will have CPU frequency set to
266MHz temporarily, so you will have to apply that frequency by issuing the keep cpu frequency command
in the loader configuration prompt.
Thanks all for the feedback. I should’ve asked this before hanging a bunch of these. I thought I recall reading somewhere that you can up the frequency without using the console, as long as they can be power-cycled…is this a possibility? It would be a beautiful thing to be able to change these over the air 
Since I’m asking, how about the 400MHz option? Is this strictly a heat issue? It appears that one could use thermal glue to attach a small heatsink on the CPU as long as both mPCI slots aren’t needed. Or, is it more like desktop CPUs/GPUs where some just clock higher than others?
To force change over the air try this
/system routerboard settings set cpu-frequency=330
Power cycle after prompt returns. After reboot type
/system routerboard settings keep-frequency
For good measure, since it gets hot here in the summers, I buy “ramsinks” from newegg.com that come with self-stick thermal pads and slap those on the RB CPU. Just a little extra measure of comfort, the downside being that you can’t use the CF slot if you put a heatsink on the cpu.
I think you can repeat the first line twice, and then keep-frequency and you don’t even need to reboot …
Sam
Thanks for posting this info NZLamb and changeip 
I’ll give this a try and see what happens. Hope it goes okay as these routerboards are not easily accessable! I agree on the ramsinks…I wonder what the temp threshold is on these at 330MHz.
The RC32434 is guaranteed in an ambient temperature range of 0°
to +70° C for commercial temperature devices and - 40° to +85° for
industrial temperature devices.
Ta Industrial Ambient Operating Temperature -40 +85 °C
Ta Commercial Ambient Operating Temperature 0 +70 °C
Ts Storage Temperature -40 +125 °C
I use small self-adhesive heatsinks on overclocked RB’s too. I thought I was just being paranoid; I don’t know if they make a lot of difference however nothing has crashed as of yet. Any other opinions?
I run all my 532’s at 330Mhz, all of them in the pac-wireless metal outdoor box (from wisp-router) and even in 90 deg weather i haven’t had a single issue.
Good thread guys - thanks a lot.
As an aside, I found that I couldn’t execute the set cpu-frequency command from inside winbox - for some reason it kept reseting the connection (between winbox and router), when I reconnected, there was no difference to the speed setting.
Worked fine executing the command by SSH. Although it still dropped the connection to the winbox running in the background, the SSH connection remained up.
Shut down, toggled the power and ran keep-frequency (from SSH, didn’t try winbox terminal), and now everything seems to be fine.
Thanks again!
Edit: Oh, and I couldn’t use 333mhz, something about it not being a recognised setting. Had to use 330Mhz instead. I can live with this (although I did pay for 333mhz…hmmm, can I get a refund on those 3Mhz? 
)
just an update, we’ve had a huge heat wave over the last week or two, we’ve recorded temperatues as high as 112.2F at our office. We have a weather station on our roof, right next to one of our APs (532 and a SR2) that is mounted in a one of the Pac Wireless boxes, and we have another 532 right above that box with a CM9 in a rootenna (grey not white) and again, no problems running at 330MHz…
Any way to go ABOVE 330Mhz?
I saw something about a 400Mhz version (on request)
Is there an option to “test” bigger frequencies than 330Mhz?
I just have upgrade RB 532 with mt 2.9.31 to 2.9.32 and there is no cpu-frequency=330MHz !
MT said that will be fixed on 2.9.33
Regards