Does reducing CPU frequency on RB433AH reduce peak power use?

I have a RB433AH which is only at 10%, or less, CPU use.
It has two R5H radio cards and sometimes it reboots because there isn't enough power.
It's already on a 24V 50W power supply, but the cable voltage drop is just too great and I don't know of any high power supplies between 24V and 28V.

If I lower the CPU speed, to something like 300 MHz or 200 MHz, will it reduce the power usage enough to keep it running without reboots when both radio cards are on TX?

I know I could reduce TX power on the radios, but that's not an option here.

anybody knows?

Did you ever get an answer or find out?

I was wondering about the same now in a scenario that has come up.

I have a 433GL card, but core question remains the same. Will the peak poweruse go down by reducing CPU Frequency.

I would try to install better cable and/or rise input voltage if you think that the voltage is insufficient. What have you measured on the device when it was running?

Yeah, I figured the same.

I increased the power-source from 12v to 24v, and now seems to work fine! I will replace this powersupply with a 12v->24v DC/DC converter when I get it so I get my battery backup back soon.

Strange thou, I have had MT equipment(RB333+R52H+2xR52) running on 12v battery power nicely on the same setup for several years withouth problem.
But I guess the newer RB433GL and 3xR52Hn Radiocards simply draw more power then the older once, thus increasing the resistance in cable and voltage-drop.



BTW, to address the initial question, I also tried lowering the CPU-Freq. to lower powerconsumption (Togheter with reducing TX-power on radiocards and disabling 1 card).

In my experience the lowering of CPU-freq. didnt do a thing!
The lowering of TX-power did just a LITTLE BIT(0,1-0,2v) and can maybe be used as an emergency fix for a little while, but only really viable course of action is to increase input voltage from beginning to get good result.

Sure because cpu is almost everytime idle so frequency change doesn't have effect. It's always better to power devices with higher voltage as the current drain could be lower. I use notebook power supplies when powering more devices as they supply around 20v really stable and with big reserve. And they are for free because of already disposed old computers there is a surplus of these power supplies.

Think about 24v battery backup with 27v power supply. You will get better effectivity if you will not use voltage step up converters.

CPU down clock will not reduce power usage significantly, as that CPU is using ~1W at whatever frequency you are running it.

As other have mentioned - you can use 24V battery at the router. So it is supplied with stable 24V or use higher voltage power supply to power it up (28V is at the upper bound and supported by us) PSU output is not so important as long.

while you search for the solution you can limit tx-power for lower data rates, or make sure that your link uses higher/hiest possible datarates as these usually come with reduced tx-power output. As those wifi modules are the cause of the the problem as router alone uses 2 - 3W tops. (Consumption on RouterBOARD.com usually is with WIFI modules and power delivery circuitry strained to maximum)

CPU down clock will not reduce power usage significantly, as that CPU is using ~1W at whatever frequency you are running it.

As other have mentioned - you can use 24V battery at the router. So it is supplied with stable 24V or use higher voltage power supply to power it up (28V is at the upper bound and supported by us) PSU output is not so important as long.

while you search for the solution you can limit tx-power for lower data rates, or make sure that your link uses higher/hiest possible datarates as these usually come with reduced tx-power output. As those wifi modules are the cause of the the problem as router alone uses 2 - 3W tops. (Consumption on RouterBOARD.com usually is with WIFI modules and power delivery circuitry strained to maximum)

Thx for clarification janisk, and:" (Consumption on RouterBOARD.com usually is with WIFI modules and power delivery circuitry strained to maximum)" was particular interesting to know. I have always been a bit unsure how the power consumption was calculated on Routerboard.com. Good to know it takes Radiocards into account! Makes planning a lot easier!

I use 24v batterybackup packs most places where I have longer cables to powerjack. But some places like this current one I have very limited space for more batteries, thus I'll just use a converter on present 12v battery to up the voltage to 24v and still have reasonable backup time. Even thou I am aware that the converter "steals" some power.

Thx all for quick responses!

for RB344AH 10V - 12V range should be fine too if powered by plug from batteries.

yes reducing the frequency does reduce peak power use, however you dont get much power saving doing so unless you need to spare 1 or 2Watts. Other things onboard do use power such as wifi, ethernet and such. I dont think mikrotik has made power saving for routerOS yet. Newer switches have power saving from cable lengths and unplugged ports to save a few watts.

If it uses a MIPs CPU dont expect much power difference by underclocking/overclocking the CPU.

whole router without cards uses ~2W and not all of that is used up by CPU. Reducing CPU frequency will reduce power consumption by level that can be written off as statistical measurement error.

On the other hand if you have mediocre wifi link with high power modules and you improve that so that it always stays in higher data rates will reduce consumption from 6W down to 3W. And that is a lot.

Also, as Ethernet interfaces on the router are 100Mbit you will see some power saving when cable is not plugged in.