I have a question regarding VIM1 CPU temperatures reported by lm-sensors. Its 46 Celsius idle/under small load ~20% per 1CPU (mpd and spotify servers). The unit is cooled passively by the native Khadas radiator with thermopad behind it. I tied the radiator very gently, since if the screws are fully tightened then the board visibly deforms in an arc.
Under heavy load the CPU temperatures reached more than 70 degrees!
Do you think that at least at the idle/small load the temps of 45-46Celsius are safe for the board in the long term (I mean many hours a day)?
I like to board very much, I managed to install libspotify and mpd server to play music through the Khadas Tone board on my stereo.
Hello, What are your ambient temps(room temp)? 45-46C is not harmful. I think the SoC starts to throttle around 70C. Throttling prevents damage but reduces performance. As with all electronics, less heat equals better performance, longer life and more stability. Your temps are not alarming, however, I shoot for 60c or less under heavy load. In my tech space, ambient temps are high so I use HS and fan.
Sure, looking at the CPU temperatures was the first thing I did after installing my system (latest ubuntu) and I am keeping eye on it. Since I am using the board as my DAC, I lowered the CPU frequency to max 667MHz, which is still sufficient, 1CPU is under 11-20% load
current policy: frequency should be within 500 MHz and 667 MHz.
The governor “powersave”
But I think it still relatively warm, though I have some other devices working at this temps range (Raspberry Pi 1, no heatsink, temps around 44C, months of stable work, ADSL router, around 50 degress - stable).
The VIM1 board under full load certainly overheats badly, and a fan would be the must.
Ive gone round and round with temps dont let them fool you, i can see improvements when using these boards the cooler they are the faster they run.
Now just because they say “throttling doesnt start till yada yada temps” you have other components on these boards and they are affected by heat also.
Most of us run the CPU with little pads that connect the ram, and memory chips to the CPU so if the CPU is running at 40-50C then that means the ram and memory is too and it ALL matters in the end. You cool the CPU but leave the memory running hot you STILL have resistance.
If heat didnt matter why even run a heatsink at all? why add a fan? why are they just now releasing a larger heatsink? why is there a DIY case with “metal plate” and without?
Why is there a 5mm gel pad you can add to transfer heat from the BACK of the board to the metal plate? BECAUSE it all matters!! All these little things add up to an end result
Think of it like a race car, you cant run a super engine and bald tires, you cant run a super engine and good tires with no suspension, you cant run a super engine, good tires, good suspension and a poor driver.
What ive found is you need to keep the temps as low as you can with out the device ramp up in temps quickly. If you see temps slowly ramping under load your cooling isnt enough, if they jump quickly thats worse the longer you can hold the temps low the better like a large dense sink will take longer to heat it up so the temps dont ram up and down the slower they ramp the better.
The larger passive sink they are releasing will be good but adding a fan to the larger sink will be better
VIM3 and VIM3L are the only boards, which can sustain 100% load and with a simple heatsink without Fan,
all the other boards need the Dedicated “passive heatsink” to be able to maintain 100% load capacity without throttling,
( of course these are for 30° Celsius ambient temprature)
If your work environment is cool and calm maybe even a bit windy it means a small cooler is ok…
Here it is hot and humid in the day, but cool and windy as soon as it becomes 4pm in the evening,
I now understand the paradox: damping the maximum CPU frequency to 667MHz or even to 250MHz (just a test) does not cool the board - I noticed it has some equilibrium at almost-idle-state, (true idle or when CPU load is low). And no matter how low is the frequency, after half an hour lm-sensors report somewhat constant temperature around 45 degrees. So that must be the RAM responsible, since the thermopad connects 4 chips. And the board is hanging freely in the air. Perhaps hetsink screws should be tightened better but as I wrote before, when I did that the board deformed visibly into an arc on the side of GPIO. Perhaps the pad is too thick a bit.
Those pads squish down more when they get hot, i always call em gummy bears and they kinda work like that as they get hot they squish down and make better contact and soften up more.
Are you using one of the DIY cases khadas makes? does it have the metal plate at the bottom? if it does grab one of those 5mm gel pads it can sadwhich the board between the gel pads and even help cooling even more
I have to many of these cases so i found one 100mmX100mm X5mm and cut it up as i needed it
The Vim1 has ram on the bottom so i cut on longer to slide under those ram chip and then conect to the metal plate also, here again the heat transfering from the bottom of the board im heating the bottom ram chips, but its hard to say if im helping or hindering them
I don’t think the ram chips produce that much heat, there are a lot of moving parts in the system, the heat can be produced from each part…
you better look at the heat trapped between the board and other parts…
If you have ever seen a desktop PC, you will have seen that it has many cooling fans on it, the reason is to constantly replace the air to maintain the cooling effect without creating a cooling potential on one side and and heating potential on the other…
I have no case/metal plate, just the Khadas heatsink attached to the board with stock screws. Thank you for pointing this out, I am going to buy the metal plate with a case or install a small and silent fan.
Sure, but my board hangs just freely without any case and there is a lot of space around, no additional heat sources. I think that it is the thermopads that do not work properly since I was afraid of tightening the heatsink too much.