Forum > Debian
bronco 看全部
2015-12-4 16:31:46


hojnikb replied at 2015-12-4 16:07
Is it possible to go lower with the voltage ?
Something like 800mV for 240Mhz.

Maybe this works. But it's already below the recommended minimum according to the user manual. And it doesn't help that much with further savings.

The other end of the scale is more interesting since a slight increase in voltage leads to massively more consumption/heat. I can't explain it well since I'm an electrics NOOB so better read from here on: https://olimex.wordpress.com/201 ... -way/#comment-20385

And this is exactly the reason the Orange Pi Plus/2/PC users suffer from heat problems: Since the dvfs settings used with every OS image are broken: Only 2 voltages defined, the upper beyond specifications (1.5V) and the lower also on the upper limit (1.3V). By simply adjusting these to sane values und using a few more dvfs table entries all the problems are gone.

And for my use cases the H3's 4 cores are great since you can operate the SoC at low clockspeeds (then also low voltages) what really helps lowering consumption/heat. This is where the H3 can really shine: http://www.orangepi.org/orangepi ... 6&fromuid=29411
hojnikb 看全部
2015-12-5 00:27:41
I suppose recommended minimums are meant for stable operation for even the crappiest quality bins.

But the bigger question is whenever it actually sets 800mV if you define it in the dvfs table or just ignores it and sets the recommended minimum.

Defenetly needs testing.
bronco 看全部
2015-12-6 02:46:19


hojnikb replied at 2015-12-5 00:27
I suppose recommended minimums are meant for stable operation for even the crappiest quality bins.


You might run into stability problems. And the potential savings aren't worth the efforts.

It makes nearly no difference regarding consumption/temperature when you decrease voltage from 900mV to 800mV but it's a completely different story at the upper limit of the scale: 1400mV vs. 1500mV make a huge difference. By simply stopping this overvolting most of the heat/stability problems (and the need for a fan) are gone.
bronco 看全部
2015-12-7 07:02:33
A few final words: http://linux-sunxi.org/User_talk ... e_Frequency_Scaling

I let the test script also walk through my 'headless' settings with further reduced voltage (on the right):

It's not worth the efforts to undervolt further. The most important change is to escape from Xunlong's overvolted dvfs table with only 2 entries leading to all sorts of heat/stability problems the forum is full of.
zgoda 看全部
2015-12-8 00:23:58
Thank you for your work. Stability is my main concern so I will definitely follow your advice.

OPi PC will be working in my beer cellar, any additional heat dissipation is not welcome.

OrangePi En

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