Has anybody ever stacked two CPU coolers?...

[Commander Kinsey]

On Mon, 27 Jul 2020 00:26:31 +0100, Ricketty C <gnuarm.deletethisbit@gmail.com> wrote:

On Sunday, July 26, 2020 at 5:19:03 PM UTC-4, Commander Kinsey wrote:
On Sun, 26 Jul 2020 20:18:46 +0100, Ricketty C <gnuarm.deletethisbit@gmail.com> wrote:

On Sunday, July 26, 2020 at 2:54:10 PM UTC-4, Commander Kinsey wrote:
On Sun, 26 Jul 2020 18:37:23 +0100, Ricketty C <gnuarm.deletethisbit@gmail.com> wrote:

On Sunday, July 26, 2020 at 1:03:55 PM UTC-4, Commander Kinsey wrote:
On Sun, 26 Jul 2020 17:14:59 +0100, Ricketty C <gnuarm.deletethisbit@gmail.com> wrote:

On Sunday, July 26, 2020 at 5:43:51 AM UTC-4, Martin Brown wrote:
On 25/07/2020 22:39, Commander Kinsey wrote:
On Sat, 25 Jul 2020 21:09:52 +0100, legg <legg@nospam.magma.ca> wrote:


Stacking CPU coolers will have a huge impedance mismatch on the second
one - essentially wasting most of its capability.

A highly faulty analysis.

People often think the best match for power is equal impedance, but that is not the case when the impedance of the load is fixed.

It is in stereos.

That shows you didn\'t understand anything I wrote.

I understood it perfectly. I was pointing out that you were not correct in all cases. In a stereo the impedance of the load is fixed, the speaker doesn\'t change.

If you fix the load impedance, what do you change? If you can\'t change anything there is nothing to compare. So again, you fail to understand what I wrote.

You compare different source impedances duh. That\'s the only variable left.

So what happens as you lower the source impedance? At what point do you get the most power into the load?

https://en.wikipedia.org/wiki/Impedance_matching

And no it doesn\'t make sense to me either. Zero source impedance would surely put the full voltage into the load and a higher current.

In that case the lowest possible impedance in the supply provides for the optimum power transfer. That\'s why power supplies are designed with very low output impedances. Same thing here, only the guy is trying to optimize his costs, rather than ultimate effectiveness of the cooling.

I have no idea what his heat sinks look like or how he plans to attach them, but adding a second heat sink will most likely improve his cooling. The only question is by how much.

Ah so now you admit my idea was sensible.

No, again, you don\'t understand what I wrote. I can make a car go faster from a start by dumping the clutch. Doesn\'t mean it\'s a good idea or \"sensible\". Read what I wrote... carefully.

Dumping the clutch causes damage, my idea would not.

That doesn\'t equate to sensible. It was a lame idea that you came up with because of a failure to diagnose the real problem, lack of air movement. Clearly the idea of fixing a lame fan by adding another heat sink is a lame idea.

No, because it would have worked, and would have been quieter than a powerful fan.

1) You don\'t know if it would have worked because you have no idea how much heat would have found it\'s way into the second heat sink.

Since the top of the 1st heatsink was just as hot as the bottom, I\'d say quite a lot.

> 2) You said \"quiet\" didn\'t matter because the rig is in the garage.

Doesn\'t matter as much.

> I don\'t know why you keep going on about this. You eventually diagnosed the real problem and got a fix. The idea of stacking heat sinks is not very practical and may or may not have \"worked\" since there is no clear definition of \"worked\".

What if it was impossible to get a fan powerful enough?

 

[Ricketty C]

On Monday, August 10, 2020 at 7:15:59 PM UTC-4, Commander Kinsey wrote:

On Mon, 27 Jul 2020 00:26:31 +0100, Ricketty C <gnuarm.deletethisbit@gmail.com> wrote:

On Sunday, July 26, 2020 at 5:19:03 PM UTC-4, Commander Kinsey wrote:
On Sun, 26 Jul 2020 20:18:46 +0100, Ricketty C <gnuarm.deletethisbit@gmail.com> wrote:

On Sunday, July 26, 2020 at 2:54:10 PM UTC-4, Commander Kinsey wrote:
On Sun, 26 Jul 2020 18:37:23 +0100, Ricketty C <gnuarm.deletethisbit@gmail.com> wrote:

On Sunday, July 26, 2020 at 1:03:55 PM UTC-4, Commander Kinsey wrote:
On Sun, 26 Jul 2020 17:14:59 +0100, Ricketty C <gnuarm.deletethisbit@gmail.com> wrote:

On Sunday, July 26, 2020 at 5:43:51 AM UTC-4, Martin Brown wrote:
On 25/07/2020 22:39, Commander Kinsey wrote:
On Sat, 25 Jul 2020 21:09:52 +0100, legg <legg@nospam.magma..ca> wrote:


Stacking CPU coolers will have a huge impedance mismatch on the second
one - essentially wasting most of its capability.

A highly faulty analysis.

People often think the best match for power is equal impedance, but that is not the case when the impedance of the load is fixed.

It is in stereos.

That shows you didn\'t understand anything I wrote.

I understood it perfectly. I was pointing out that you were not correct in all cases. In a stereo the impedance of the load is fixed, the speaker doesn\'t change.

If you fix the load impedance, what do you change? If you can\'t change anything there is nothing to compare. So again, you fail to understand what I wrote.

You compare different source impedances duh. That\'s the only variable left.

So what happens as you lower the source impedance? At what point do you get the most power into the load?

https://en.wikipedia.org/wiki/Impedance_matching

And no it doesn\'t make sense to me either. Zero source impedance would surely put the full voltage into the load and a higher current.

Exactly what it does. You seem to fail to understand what you are reading....

\"Whenever a source of power with a fixed output impedance such as an electric signal source, a radio transmitter or a mechanical sound (e.g., a loudspeaker) operates into a load, the maximum possible power is delivered to the load when the impedance of the load (load impedance or input impedance) is equal to the complex conjugate of the impedance of the source\"

See the first few words set the conditions for this rule to be valid?

So it seems I was right when I wrote, \"That shows you didn\'t understand anything I wrote\".

In that case the lowest possible impedance in the supply provides for the optimum power transfer. That\'s why power supplies are designed with very low output impedances. Same thing here, only the guy is trying to optimize his costs, rather than ultimate effectiveness of the cooling.

I have no idea what his heat sinks look like or how he plans to attach them, but adding a second heat sink will most likely improve his cooling. The only question is by how much.

Ah so now you admit my idea was sensible.

No, again, you don\'t understand what I wrote. I can make a car go faster from a start by dumping the clutch. Doesn\'t mean it\'s a good idea or \"sensible\". Read what I wrote... carefully.

Dumping the clutch causes damage, my idea would not.

That doesn\'t equate to sensible. It was a lame idea that you came up with because of a failure to diagnose the real problem, lack of air movement. Clearly the idea of fixing a lame fan by adding another heat sink is a lame idea.

No, because it would have worked, and would have been quieter than a powerful fan.

1) You don\'t know if it would have worked because you have no idea how much heat would have found it\'s way into the second heat sink.

Since the top of the 1st heatsink was just as hot as the bottom, I\'d say quite a lot.

Not really. Equal temperature does not imply equal heat carrying. You yourself said you only measured the temperature with your finger. Elsewhere you talked about the thermal interface with the CPU being the limiting impedance, not that it is true. The point is you are all over the map on this topic.

2) You said \"quiet\" didn\'t matter because the rig is in the garage.

Doesn\'t matter as much.

I don\'t know why you keep going on about this. You eventually diagnosed the real problem and got a fix. The idea of stacking heat sinks is not very practical and may or may not have \"worked\" since there is no clear definition of \"worked\".

What if it was impossible to get a fan powerful enough?

Whatever that means.

It is important to actually understand a topic if you are going to analyze it. Otherwise you are just a hack trying this and trying that. Not that there is anything wrong with that method. Some awesome stuff has been built by trial and error. But you need to recognize when you are doing that and not insist that something would have worked because a part of the heat sink \"felt hot\" to your finger.

It\'s time to give it a rest.

--

Rick C.

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