FAN installation on PX5

[giouncino]

I was at the store last night and just happened to walk by some original Intel PII heatsinks I thought those would work nicely with those little 5ish Watt SoC; low profile, light weight and a quiet fan. I'm a little concerned about the extra weight my HU is a slim type all the electronics are sitting vertically. The road vibration and heat in a car would put a lot of strain on those 2 little mounting screws and there's only 3 dabs of silicone holding the connector in place. They should have put at least 1 more screw on a different plane to really secure the SoM.

Can't say much good about using a cast shield as a heatsink either. What is that material, recycled aluminum. Probably not the best for heat transfer, the pitted surface definitely is not. I hope they used a heat transfer pad between the SoC and the shield and not silicone. I'm sure it's all good enough but it's definitely not meant to last long.

in my case, PX5 board is orizzontally mounted, so the heatsink weight is don't care.

 

[woozie.2007]

This is what i made with your help, in idle i have 13 degrees, and full load maximum 75 degrees. Thank you all, especially giouncino

 

[giouncino]

Very good job! This intel heatsink with copper core is simply perfect! Well done!

 

[IloveJapan]

Hello,

I've improved the cooling on my PX6. First I've check how Rockchip CPU is link to the radiator: It's a poor quality thermal pad (not correctly centered)

I've tested if I can use thermal paste instead of thermal pad, but distance from SOC cover to the radiator is to far to be better than pad.

So I changed original pad to an high quality pad, correctly centered.

then I installed an Intel CPU radiator over the original one (with thermal paste between the 2 radiators) to improve heat exchange:

I was needed to cut lot of fins to be sure to create no interference with other component on the SOM.

Fitted in the unit:

I've tested the modification with several geekbench loops, temperature was 20°C less, but heat seemed to stay inside the unit enclosure. So I tested without top cover and temperature drop again 10°C. So I decided to modify top cover, without installation of a fan, to create a natural airflow.

Results are good, now the SOC never throttle, even after 5 loops of geekbench or GFX bench, temperature increase slowly from 45°C (idle) until reaching a maximum of 72°C

 

[kmlnvm]

Hello,

I've improved the cooling on my PX6. First I've check how Rockchip CPU is link to the radiator: It's a poor quality thermal pad (not correctly centered)

I've tested if I can use thermal paste instead of thermal pad, but distance from SOC cover to the radiator is to far to be better than pad.

So I changed original pad to an high quality pad, correctly centered.

then I installed an Intel CPU radiator over the original one (with thermal paste between the 2 radiators) to improve heat exchange:

I was needed to cut lot of fins to be sure to create no interference with other component on the SOM.

Fitted in the unit:

I've tested the modification with several geekbench loops, temperature was 20°C less, but heat seemed to stay inside the unit enclosure. So I tested without top cover and temperature drop again 10°C. So I decided to modify top cover, without installation of a fan, to create a natural airflow.

Results are good, now the SOC never throttle, even after 5 loops of geekbench or GFX bench, temperature increase slowly from 45°C (idle) until reaching a maximum of 72°C

I don't know if these holes are ok because after sometime unit can collect dust inside.

 

[nic2k]

Maybe it depends where you live but I've never pulled out a car radio that was covered in dust even after years in the car. The inside of a dashboard is a pretty clean place compared to the rest of the car or my garage.

 

[uncleee]

heatsink

If you put a heatsink on top of origenel heatsink of px5 som board can you cover the holes with heatsink or leave them open ? i think if you cover them theres no airflow for the holes i saw a lot of fotos with the heatsink covering them?

 

[giouncino]

The holes on original metal plate are totally useless, don't worry

 

[nic2k]

I suspect the holes are mostly there for appearance and maybe to reduce the weight rather than allow airflow. There's not much gap at the base to allow air in and through the holes and most of the convection would be around the outside of the plate. The plate is an EMI shield for the electronic components. The material and finish is less than ideal for a heatsink but it was just convenient to use it to give the SoC the extra cooling it would need in the car environment. Those SoC are meant to be used without heatsink in things like tablets and TV boxes.

 

[woozie.2007]

since i made the modification on my unit, no one random reboot, no any stop of app, everything works perfect, before i made the mod, especially apps for navigation after around 150km, gave me force close and i had to open it again, but now i made 3000 km with waze and igo and nothing happened, it works continously without any stuck.

 

[Barreto]

Hi.

I've been following this thread for a while now. Had a PX3 and just bought a PX6, so I was waiting on the new unit to try these mods.

What do you guys think of applying a heatsink directly on the chip? IE: remove the top plate (original heatsink), stick a heatsink (from a raspberry pi, maybe?) directly on the CPU chip and leave it like that. This would improve heat dissipation because there would be direct contact between the chip and the new heatsink.
As far I can tell from the pictures above, the other chips don't make contact with the top plate (og heatsink), so there shouldn't be a problem leaving them in the "open", right?

I've used small heatsinks on rasp pis before and they do a good job... I'm talking about something like the blue one on this site

I don't mind trying it, I just would like to know if you guys know of any reason not to do it. Or if you think this heatsink is too small to keep the temps in check.

Thank you
(and good job on your mods, they are really cool)

 

[giouncino]

This kind of heatsink are good for cool down ram modules generally, I would use a bigger heatsink for the soc, even if it is only a 4.5w the temps of this chip raise very quicky, so it's a good idea to use a bigger heatsink.
Other than that it's perfect to remove the metal plate and put heatsink in direct contact with the SOC, but you should manage to stick the heatsink firmly and it's not simple considering car vibrations during use that can break the chip.

 

[Barreto]

This kind of heatsink are good for cool down ram modules generally, I would use a bigger heatsink for the soc, even if it is only a 4.5w the temps of this chip raise very quicky, so it's a good idea to use a bigger heatsink.
Other than that it's perfect to remove the metal plate and put heatsink in direct contact with the SOC, but you should manage to stick the heatsink firmly and it's not simple considering car vibrations during use that can break the chip.

Yes, I see your point.
Unfortunately, I don't think I can find a heatsink that is small enough to just stick to the chip and big enough to provide enough heat dissipation. Seeing that you guys are successfully getting temps down with a heatsink stuck to the plate, I might just buy 2 of these (40x40x30mm) and put them there.

BTW: replacing the thermal pad between the chip and the top plate makes a big difference? I was thinking of buying something like this. Do you know what thickness I should buy? They go from 0.5mm to 2mm

Again, thank you for your inputs.

 

[giouncino]

i bought this one:
https://www.amazon.it/gp/product/B07PNL9C1Q/ref=ppx_yo_dt_b_asin_title_o02_s01?ie=UTF8&psc=1
and used 0.5mm to replace original thermal pad.
buying two heatisink 40x40x30 should be sufficient to see a good difference in temps

 

[marchnz]

I'll say it again; use thermal adhesive - you want a very thin layer between the source and sink.

Thermal adhesive is readily available from most electronic suppliers or online.

 

[Barreto]

I'll say it again; use thermal adhesive - you want a very thin layer between the source and sink.

Thermal adhesive is readily available from most electronic suppliers or online.

As far as I understand it, there is a significant gap between the chip and the top plate. @IloveJapan tried using thermal paste and said it wasn't making significant contact (and the pictures showed it)

Going with @giouncino info, I'll be using a 0.5mm thermal pad.

Do you think this is not the best way to go? What is the difference between a thermal pad and thermal adhesive?

 

[giouncino]

Yes, the gap is significant.
I don't know if thermal adhesive is strong enough to keep a big and heavy heatsink in place, In my case I don't think so. But with a 40x40x30 light heatsink as yours it could be sufficient and probably you can use thermal adhesive directly on Rockchip SoC, removing the metal plate.

 

[nic2k]

Not a good idea to have a BGA chip carry the weight of a heatsink those little solder balls don't do too well under mechanical stress. The heatsink should be attached to the PCB. The plate is screwed to the PCB so it can hold the weight of the heatsink no problem.

 

[Barreto]

Not a good idea to have a BGA chip carry the weight of a heatsink those little solder balls don't do too well under mechanical stress. The heatsink should be attached to the PCB. The plate is screwed to the PCB so it can hold the weight of the heatsink no problem.

Yeah, you guys are prob right. The heatsink is really light, but the vibrations from a moving car could make it bounce a lot and damage the chip...
I will just replace the thermal pad between the chip and top plate, remount the top plate and attach the heatsinks to this plate.

I tested temps this weekend, and they were around 80C with music+GoogleMaps. Outside (ambient) temps were around 30C. (under stress was about 95C, but that is not normal use...)
If it lowers 20C, I'll be happy.

I will try to post some pics of the procedure when I receive the materials. (it shouldn't be very different from @IloveJapan post, but nevertheless...)
It should take about 1 month or so...

 

[ZigBrick]

Thanks all for the ideas. I had throttling problems with my unit when I parked in direct sunlight. It can easily reach 40° Celsius under the shade in summer here, so imagine how it is like inside a car parked in direct sunlight for a few hours in such a climate.

I used a simpler approach though.. bolted a single 60mm 12v fan directly on top of the PX5 metal cover using the same screws. Fed the power from a 9v regulator to help bring the speed down and decrease the fan noise. Also added a hidden switch to turn off the fan completely when it's winter and unneeded.



Now everything is perfect. Within a few seconds from turning on the ignition and A/C, the CPU temperature drops from like 70° Celsius to like 50° Celsius! I can even run a stress test with no observed throttling in such temperature conditions.