Topics

Fans, Pi4, and the DRAWS case

Chris Metcalf
 

Not to throw a wrench in things, but will there be a provision for adding a fan to the DRAWS case?

I've been experimenting with my Pi4, and unlike the Pi3, it runs quite hot - hot enough that the little Pi3 style heat sinks aren't enough to keep it from going into thermal throttling mode and slowing itself down. This has been documented in early reviews: https://www.jeffgeerling.com/blog/2019/raspberry-pi-4-needs-fan-heres-why-and-how-you-can-add-one

I bought a cheap plexiglass "ice cream sandwich" case (https://www.amazon.com/gp/product/B07T3DRB1C/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1) and modded it with taller risers to accommodate my DRAWS hat. But even its open design didn't allow the Pi4 to cool itself when it was loaded up, and I quickly hit 80C and started seeing performance degradation. 

I zip-tied the small fan that came with the case to one of the risers, blowing across my heat sinks, and the temperature quickly dropped down to 40C and stayed there. 

I'd still rather have the protection of the full case, but I'd be worried that it'll turn into a little metal sauna...

IMG_2032.jpg

Thanks,
Chris

 

Chris,

Could you document what SW you are running and what is your ambient temperature?

Also what does top show for cpu utilization?

And yes fans are under consideration

Chris Metcalf
 

Sure thing! Ran a little test this morning:

21C (69F) ambient temperature

- 2019-07-31 7:15:45: WSJT-X, Fan, 4% CPU, 39C
- 2019-07-31 7:16:52: Fan off
- 2019-07-31 7:19:15: 50C
- 2019-07-31 7:35:14: WSJT-X, Fan, 10% CPU, 68C (Likely throttling)
- 2019-07-31 7:35:57: Launched CubicSDR
- 2019-07-31 7:37:56: 56% CPU, 78C
- 2019-07-31 7:38:31: 55% CPU, 80C
- 2019-07-31 7:40:35: 63% CPU, 83C
- 2019-07-31 7:41:06: Fan on
- 2019-07-31 7:41:40: 56% CPU, 72C
- 2019-07-31 7:44:32: 56% CPU, 56C
- 2019-07-31 7:45:42: 40% CPU, 52C

This is running on a stock Raspbian image with apps and config set up via the n7nix scripts. Connecting via VNC.

Thanks,
Chris


On Wed, Jul 31, 2019 at 7:06 AM Bryan Hoyer <bhhoyer@...> wrote:
Chris,

Could you document what SW you are running and what is your ambient temperature?

Also what does top show for cpu utilization?

And yes fans are under consideration


Steve Stroh
 

It's a personal perspective, but I don't want a fan on an appliance
like a DRAWS. Fans are noisy. They suck dust in and spray it all over
the board. They're non-static hardware that will inevitably fail.

I hope to build up my DRAWS units as (silent) appliances, and tack
them up and out of the way on a shelf, or wall, or ??? and access them
remotely.

The extra power (and the 2 GB or 4 GB of RAM) of the RPi4 is nice, and
I plan to have at least a couple, probably as standalone workstations,
but on the DRAWS, I haven't seen / heard / read anything that
indicates that the additional power of the RPi4 would be of any
benefit to a DRAWS unit above and beyond what the RPi3 does. Thus, the
RPi3 which doesn't need a fan, is preferable to the RPi4, which does
seem to need a fan, for use on DRAWS.

Thanks,

Steve

On Wed, Jul 31, 2019 at 7:06 AM Bryan Hoyer <@K7UDR> wrote:

Chris,
<snip>

And yes fans are under consideration
--
Steve Stroh (personal / general): stevestroh@...

JT Croteau
 

I am hoping the Pi 4 draws less than 20W.  I run completely on solar power and looking for a desktop replacement with DRAWS.  Fan noise can be mitigated.   I have a 2n1 laptop/tablet that draws about 25W but I'd much rather have the DRAWS and some other apps in one device.


On Wed, Jul 31, 2019, 16:23 Steve Stroh <steve.stroh@...> wrote:
It's a personal perspective, but I don't want a fan on an appliance
like a DRAWS. Fans are noisy. They suck dust in and spray it all over
the board. They're non-static hardware that will inevitably fail.

I hope to build up my DRAWS units as (silent) appliances, and tack
them up and out of the way on a shelf, or wall, or ??? and access them
remotely.

The extra power (and the 2 GB or 4 GB of RAM) of the RPi4 is nice, and
I plan to have at least a couple, probably as standalone workstations,
but on the DRAWS, I haven't seen / heard / read anything that
indicates that the additional power of the RPi4 would be of any
benefit to a DRAWS unit above and beyond what the RPi3 does. Thus, the
RPi3 which doesn't need a fan, is preferable to the RPi4, which does
seem to need a fan, for use on DRAWS.

Thanks,

Steve

On Wed, Jul 31, 2019 at 7:06 AM Bryan Hoyer <bhhoyer@...> wrote:
>
> Chris,

<snip>

> And yes fans are under consideration

--
Steve Stroh (personal / general): stevestroh@...



Jeff NE1U
 

I like the idea of not having to have a fan ... maybe. lol

Orienting heat sink fins vertical and given that warm air flows up, makes the best use of passive cooling. Can you tell that I am an engineer? Apologies. Probably good that there be a little air space around below and above the heatsink. 

On the other hand, the specs for fans include the dB noise level and a very quiet low speed fan can greatly improve heat exchange in any orientation. Just read the specs and investigate.

Chris Metcalf
 

FWIW, the “Pi-Fan” brand fan that came with my case is _extremely_ quiet and can barely be heard even from a foot or two away.

A big passive heat sink could possibly help, but the “hat” standard makes that difficult since the hat sits right on top of the Pi and doesn’t leave much room for a heat sink. Perhaps a later generation case could include a riser or some sort of heat pipe system to dissipate heat outside the case.

Key learning though is that it looks like the Pi4 is impractical without some sort of cooling for the CPU. I’ve still got my 3B+ and may reconsider it if the power and cooling requirements are too high, but right now I’m _loving_ the extra memory and CPU. 

-- 
Chris Metcalf

On July 31, 2019 at 2:47:43 PM, Jeff NE1U (jwalden@...) wrote:

I like the idea of not having to have a fan ... maybe. lol

Orienting heat sink fins vertical and given that warm air flows up, makes the best use of passive cooling. Can you tell that I am an engineer? Apologies. Probably good that there be a little air space around below and above the heatsink. 

On the other hand, the specs for fans include the dB noise level and a very quiet low speed fan can greatly improve heat exchange in any orientation. Just read the specs and investigate.