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Pi 4 heat sinks

Posted: Wed Jun 26, 2019 12:39 am
by PinkTricam
Hi there - anybody know what size of heat sinks would be needed for the new Pi 4? Are the CPU etc. the same physical dimensions as the Pi 3b+, for example?

Thanks for your help! Can't wait to get my hands on one :-)

Re: Pi 4 heat sinks

Posted: Wed Jul 10, 2019 11:39 pm
by pi3g
I use the same heat sinks for the Pi 4, which we use for the Pi 3B+.

Re: Pi 4 heat sinks

Posted: Fri Jul 12, 2019 10:14 pm
by energyi
I'm running without a heat sink, but with a fan blowing up direction in a open walled case and temp stays in low 40's.

Re: Pi 4 heat sinks

Posted: Fri Jul 12, 2019 10:19 pm
by jahboater
I believe the SoC heat spreader is a little higher than the surrounding components so you can fit a bigger heat sink.
Like this

https://shop.pimoroni.com/products/rasp ... 4-heatsink

or this

https://thepihut.com/products/al-heat-s ... 30-30-10mm

But if you are sensible enough not to put the Pi4 into a tiny un-ventilated plastic case, then it doesn't really need a heat sink.

Re: Pi 4 heat sinks

Posted: Fri Jul 12, 2019 10:25 pm
by HawaiianPi
I'm also using a case with a quiet, low CFM fan and no heatsink (picture is just an example). Works great!

In general, a fan alone works better than a heatsink alone (which usually just delays the inevitable throttling under heavy loads).

Re: Pi 4 heat sinks

Posted: Fri Jul 12, 2019 11:55 pm
by 313Alf
jahboater wrote:
Fri Jul 12, 2019 10:19 pm
I believe the SoC heat spreader is a little higher than the surrounding components so you can fit a bigger heat sink.
Like this

https://shop.pimoroni.com/products/rasp ... 4-heatsink
I bought one of these, but the fit seemed so tight that I was concerned about trying to wedge it into place and possibly damaging components. I have a coupe Pi4 case and ended up using a smaller heatsink (14.5 x 14.5 x 6mm from the same Company) booster header and fan-shim which works very well.

Should I have removed the Pi from the case before attempting to fit the bigger heatsink? Perhaps the board/heatsink sizes are not always consistent? (though I imagine they must be). I just wonder how others have managed to fit them in. I will find another use for it eventually.

Re: Pi 4 heat sinks

Posted: Sat Jul 13, 2019 12:19 am
by alphanumeric
313Alf wrote:
Fri Jul 12, 2019 11:55 pm
jahboater wrote:
Fri Jul 12, 2019 10:19 pm
I believe the SoC heat spreader is a little higher than the surrounding components so you can fit a bigger heat sink.
Like this

https://shop.pimoroni.com/products/rasp ... 4-heatsink
I bought one of these, but the fit seemed so tight that I was concerned about trying to wedge it into place and possibly damaging components. I have a coupe Pi4 case and ended up using a smaller heatsink (14.5 x 14.5 x 6mm from the same Company) booster header and fan-shim which works very well.

Should I have removed the Pi from the case before attempting to fit the bigger heatsink? Perhaps the board/heatsink sizes are not always consistent? (though I imagine they must be). I just wonder how others have managed to fit them in. I will find another use for it eventually.
I used that heatsink with that Pibow Coupe case. I did a test fit before removing the backing off of the 3m thermal tape. Mine fit Ok. It is a tight fit but I was careful sticking it down and it wasn't an issue. I put my case on the Pi 4 first, then attached the heat sink. I will be adding a fan shim at some point. I'll solder it to a header.

Re: Pi 4 heat sinks

Posted: Sat Jul 13, 2019 12:25 am
by 313Alf
Thanks for the info, maybe I should have tried flipping it around 180 degrees, it may have fit. It just seemed to be touching the connectors either side which concerned me. Since getting the fan-shim the size of the heatsink is probably less important now, I can keep it in the 40 to 50 degrees-C zone easily.

Re: Pi 4 heat sinks

Posted: Sat Jul 13, 2019 12:44 am
by alphanumeric
313Alf wrote:
Sat Jul 13, 2019 12:25 am
Thanks for the info, maybe I should have tried flipping it around 180 degrees, it may have fit. It just seemed to be touching the connectors either side which concerned me. Since getting the fan-shim the size of the heatsink is probably less important now, I can keep it in the 40 to 50 degrees-C zone easily.
It is close to the DSI and CSI connectors. The locking tabs for those are on the opposite sides so it was not an issue. I was more worried about the clearance to the GPIO header. I made sure to put it right up against the Pibow case top layer cutout, and as far from the GPIO as I could get it.

The fan shims were out of stock when I ordered my Pi 4 and I didn't want to chance waiting and then having the Pi 4 got out of stock. The heat sink was in stock so I added it to my order.

Re: Pi 4 heat sinks

Posted: Sat Jul 13, 2019 1:35 am
by cjan
Odroid n2 is best heat sinks design ever.

Re: Pi 4 heat sinks

Posted: Sat Jul 13, 2019 3:43 am
by Fraoch
I got a set of heatsinks with my new Pi4. I run my 3B+ with the case top off but it still runs hot and given the reports about the Pi4's heat it seemed sensible.

It came with a smaller heatsink which I presume is for the RAM, correct? It's the only other component on the board which generates any heat according to my IR thermometer: 45 C+...though the USB port casings get oddly hot after a while?

Final question: I heard reference to someone using Arctic Silver 5 heatsink compound on the heatspreader first before sticking the HS on. Wouldn't that affect the adhesive?

Re: Pi 4 heat sinks

Posted: Sat Jul 13, 2019 3:54 am
by jbeale
The purpose of a heatsink compound is to fill in small gaps, such as between the SoC and the HS. If you've got two bare metal surfaces, they will not be in good physical and thermal contact (unless they are optically flat) without something to fill in around the tiny bumps from surface roughness, like a heatsink grease or compound of some kind. BUT if you already have an adhesive pad on the heatsink, and you press it down firmly that should fill in the gaps and I don't think adding anything else will help. It would just be another layer and add to the thermal resistance.

Re: Pi 4 heat sinks

Posted: Sat Jul 13, 2019 3:58 am
by Fraoch
Makes sense, thank you.

Re: Pi 4 heat sinks

Posted: Sat Jul 13, 2019 3:59 am
by LTolledo
Fraoch wrote:
Sat Jul 13, 2019 3:43 am
Final question: I heard reference to someone using Arctic Silver 5 heatsink compound on the heatspreader first before sticking the HS on. Wouldn't that affect the adhesive?
When using heatsink compound to attach heatsink, one usually removes the adhesive thermal tapes (an all remaining residue) before applying the the heatsink compound.
apply as little as possible (as small dab will do) and spread it evenly.

most of my RPis (and other SBCs) have their heatsinks attached via heatsink compounds....

Re: Pi 4 heat sinks

Posted: Sat Jul 13, 2019 4:06 am
by rpdom
The USB socket casings get hot because they are thermally coupled to the SoC via the PCB's ground plane in order to help dissipate heat from the CPUs. The network, power and video connectors are also used in this way.

Re: Pi 4 heat sinks

Posted: Sat Jul 13, 2019 4:07 am
by Fraoch
So the heatsink compound is adhesive enough that it will adhere the heatsink to the heatspreader all on its own for months or years at a time?

I'm used to heatsink compounds on conventional desktop PCs but those have pins or latches holding the HS down very firmly.

I have both AS5 and Noctua NT-H1 compounds.

Re: Pi 4 heat sinks

Posted: Sat Jul 13, 2019 4:09 am
by Fraoch
rpdom wrote:
Sat Jul 13, 2019 4:06 am
The USB socket casings get hot because they are thermally coupled to the SoC via the PCB's ground plane in order to help dissipate heat from the CPUs. The network, power and video connectors are also used in this way.
Very interesting and efficient.

Re: Pi 4 heat sinks

Posted: Sat Jul 13, 2019 4:11 am
by scaramonga
None.

Use this:

https://shop.pimoroni.com/products/fan-shim

No heat sink required, and works rather well ;)

Re: Pi 4 heat sinks

Posted: Sat Jul 13, 2019 4:47 am
by HawaiianPi
Fraoch wrote:
Sat Jul 13, 2019 4:07 am
So the heatsink compound is adhesive enough that it will adhere the heatsink to the heatspreader all on its own for months or years at a time?
Technically, no (except for thermal epoxies).

I'm used to heatsink compounds on conventional desktop PCs but those have pins or latches holding the HS down very firmly.

I have both AS5 and Noctua NT-H1 compounds.
Correct. Most thermal compounds are designed to be used with a clamping mechanism that holds the heatsink in place and presses it into the chip. Some are viscous enough that they might hold a heatsink onto a stationary Pi computer, but they're not designed to be used that way.

There are the Kintarol heatsinks for the Pi 3B and 3B+ that are designed to be held down by the mounting holes. That interferes with a lot of case designs, but the heatsink is very effective. Not sure if it will fit the Pi4 (and I doubt it, but I haven't measured anything). I only have the older 3B version so I can't check (no cutout for the POE pins). From just a cursory glance it seems like the SoC is placed more toward the center.

Re: Pi 4 heat sinks

Posted: Sat Jul 13, 2019 5:19 am
by hommar
HTB1Nw7xXNz1gK0jSZSgq6yvwpXaD.jpg
HTB1Nw7xXNz1gK0jSZSgq6yvwpXaD.jpg (151.19 KiB) Viewed 2022 times
HTB1yvExXND1gK0jSZFyq6AiOVXaU.jpg
HTB1yvExXND1gK0jSZFyq6AiOVXaU.jpg (144.26 KiB) Viewed 2022 times
Best of the best.

Possible

Re: Pi 4 heat sinks

Posted: Sat Jul 13, 2019 5:27 am
by HawaiianPi
LOL! Yea, I posted about that one in another thread. Looks bonkers, but it will probably work great.

Re: Pi 4 heat sinks

Posted: Sat Jul 13, 2019 4:15 pm
by Fraoch
Wow. Absolute overkill but wow.