BCM4709 Temperature

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Bride
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PostPosted: Sat Dec 04, 2021 3:29    Post subject: BCM4709 Temperature Reply with quote
Hi,
I have a Netgear R8500, with a CPU BCM4709 at 1400MHz, temperature of 75 degrees and room ambient at 20 degrees. I tried to find the max temp specifications online, but without success. Within 90 degrees everything should be ok, right? I can also see that on the board, there is a 4 pins serial connector, can be used for add a fan? if yes, at which voltage? wee have a pin map? thanks
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kernel-panic69
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PostPosted: Sat Dec 04, 2021 4:22    Post subject: Reply with quote
I can't seem to find a datasheet anywhere, either; but you are within specs. I would still opt for some kind of cooling and airflow to allow for maximum heat dissipation, though. Maybe a USB-powered fan pulling air through the top of the case.
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Bride
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PostPosted: Mon Dec 06, 2021 5:22    Post subject: Reply with quote
kernel-panic69 wrote:
I can't seem to find a datasheet anywhere, either; but you are within specs. I would still opt for some kind of cooling and airflow to allow for maximum heat dissipation, though. Maybe a USB-powered fan pulling air through the top of the case.


Tks for your reply. Ok, I would like to keep cables inside the enclosure, with a tiny fan. Checking for the voltage of that serial port. Should be 5V max.
Bride
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PostPosted: Wed Dec 08, 2021 4:51    Post subject: Reply with quote
looks that someone did it


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kernel-panic69
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PostPosted: Wed Dec 08, 2021 7:59    Post subject: Reply with quote
Looks like it already had some sort of header fixture to plug into; not sure if these have a cooling fan already provided. Would be great to have a link to where you go the image/information...
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Bride
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PostPosted: Thu Dec 09, 2021 6:19    Post subject: Reply with quote
kernel-panic69 wrote:
Looks like it already had some sort of header fixture to plug into; not sure if these have a cooling fan already provided. Would be great to have a link to where you go the image/information...


It's a Chinese second hand products app, so there aren't specifications. But I just installed a small 3v fan, 70 degree, not so much difference
IONK
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PostPosted: Fri Dec 10, 2021 12:33    Post subject: Reply with quote
Bride wrote:
But I just installed a small 3v fan, 70 degree, not so much difference
was the casing still opened or already closed after you mounted the fan? it can be because there's no airflow (the vents on the plastic casing are too narrow) and the hot air keeps circulating inside the casing.
Another possibility is bad thermal paste/thermal pad.

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the-joker
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PostPosted: Fri Dec 10, 2021 14:23    Post subject: Reply with quote
Dust is a nice insulator, so anything coated in it will be nicely snug and warmer, fyi,

I use carbon coated aquarium foam and a fine filter foam around a thin layer of the aquarium foam placed where the air intakes are, and over the fan itself, I use a flex filter airflow is not impeded and the amount of dust is kept to a minimum ripe for yearly maintenance schedule.

While most specs allow for some high temperatures, TBH the greatest silicone killer is heat, shortens the life span considerably. Dust contributes to this over time.

I also replace thermal compounds for a higher performer.

A fan should considerably drop the temperatures, I prefer a bigger and lower profile fans, with more blades you can get pretty decent fans of the sort

Now if you added a fan and the best it does is 70 from 90 then theres something not right, replace the thermal grease and check the heatsinks are flush and not warped or not making appropriate contact.

Also that heatsink groves where the fan blows into are not optimal for air cooling, so the fan is far too close to the groves and only most effective area is where the fan is right over and to the bottom, leaving the lef/right are barely getting any air flow due to how the run vertically and to left/right should be horizontal so air can travel outwards in all directions.

Problem here is also if there is no source of cool air to the back of the fan on the case, consider pulling air in not pushing air in install to test how that performs..

My router however (different from yours) has external fans pushing air in, through the filter material. I will consider adding internal fans when I can take it out of commission long enough as its the main router.

Take care.

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kernel-panic69
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PostPosted: Fri Dec 10, 2021 15:41    Post subject: Reply with quote
It would have been better to use an actual photo from the R8500 as shown from the results from FCC ID search. Anyhow, if you're going to use a 12v slimline fan, you may want to tap into the power input buss(es) to get maximum efficiency. USB power will work, but it limits things some. It is really fun modifying router cases (that require it). One thing I like about the Linksys WRT AC series is that all you need to do is add one or two USB-powered fans pulling air up and through the case and done. No hack jobs required. You can also use a laptop cooling fan on some cases when you wall mount them to draw air up through the case.
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Bride
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Joined: 01 Dec 2021
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PostPosted: Fri Dec 17, 2021 13:04    Post subject: Reply with quote
IONK wrote:
Bride wrote:
But I just installed a small 3v fan, 70 degree, not so much difference
was the casing still opened or already closed after you mounted the fan? it can be because there's no airflow (the vents on the plastic casing are too narrow) and the hot air keeps circulating inside the casing.
Another possibility is bad thermal paste/thermal pad.


probably all these reasons... there is not enough space between the chassis and the fan that's already a small one. Also I replaced the thermal pads, but not enough. Thanks
Bride
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PostPosted: Fri Dec 17, 2021 13:07    Post subject: Reply with quote
the-joker wrote:
Dust is a nice insulator, so anything coated in it will be nicely snug and warmer, fyi,

I use carbon coated aquarium foam and a fine filter foam around a thin layer of the aquarium foam placed where the air intakes are, and over the fan itself, I use a flex filter airflow is not impeded and the amount of dust is kept to a minimum ripe for yearly maintenance schedule.

While most specs allow for some high temperatures, TBH the greatest silicone killer is heat, shortens the life span considerably. Dust contributes to this over time.

I also replace thermal compounds for a higher performer.

A fan should considerably drop the temperatures, I prefer a bigger and lower profile fans, with more blades you can get pretty decent fans of the sort

Now if you added a fan and the best it does is 70 from 90 then theres something not right, replace the thermal grease and check the heatsinks are flush and not warped or not making appropriate contact.

Also that heatsink groves where the fan blows into are not optimal for air cooling, so the fan is far too close to the groves and only most effective area is where the fan is right over and to the bottom, leaving the lef/right are barely getting any air flow due to how the run vertically and to left/right should be horizontal so air can travel outwards in all directions.

Problem here is also if there is no source of cool air to the back of the fan on the case, consider pulling air in not pushing air in install to test how that performs..

My router however (different from yours) has external fans pushing air in, through the filter material. I will consider adding internal fans when I can take it out of commission long enough as its the main router.

Take care.


Thanks for the detailed answer. Probably right know I can not pretend, but for sure I need to reopen it, remove the small installed fan, pretty not useful, replace all the conductive parts and reshape the chassis.
Bride
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PostPosted: Fri Dec 17, 2021 13:11    Post subject: Reply with quote
kernel-panic69 wrote:
It would have been better to use an actual photo from the R8500 as shown from the results from FCC ID search. Anyhow, if you're going to use a 12v slimline fan, you may want to tap into the power input buss(es) to get maximum efficiency. USB power will work, but it limits things some. It is really fun modifying router cases (that require it). One thing I like about the Linksys WRT AC series is that all you need to do is add one or two USB-powered fans pulling air up and through the case and done. No hack jobs required. You can also use a laptop cooling fan on some cases when you wall mount them to draw air up through the case.


Yep, I was thinking to buy a laptop cooling base, but as you said, on some way is fun to mod electronics... this router in my idea have a lot of potential, limited by thermals. So I just would like to reach at least optimal temps. Thanks for now Wink
the-joker
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PostPosted: Fri Dec 17, 2021 14:55    Post subject: Reply with quote
Good luck, and let us know how it went, with pictures would be even better =)

Take care.

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Bride
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PostPosted: Mon Dec 20, 2021 5:41    Post subject: Reply with quote
I opened this baby again and removed the fan I added previously. Removed the big black heat sink. Then I removed also the aluminum lid on the CPU part (yellow area, tks to TweakTown for the pic) and replaced the old thermal pad with a 5mm grey one, directly in contact with the big black heat sink, without the aluminum lid. For now, after 34 minutes of uptime, room temp 19C degrees and CPU temp 64C degrees. Let's see


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IONK
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PostPosted: Mon Dec 20, 2021 5:56    Post subject: Reply with quote
Bride wrote:
without the aluminum lid
the aluminum lid is for RF shielding, so probably it's better (for nearby electronic equipment, living beings, and for the router itself) to fill the gap between the chip and the lid with thermal pad, and keep the lid closed, instead of removing it.

p/s: someone is gonna scream because of the attached photos.

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Last edited by IONK on Mon Dec 20, 2021 6:02; edited 1 time in total
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