How it's made: heat sinks

Phil Hobbs wrote: ===============

...... Phil

I don't think you need to add waves to get turbulence. What is important is turbulence at the surface of the fin. The skived fins already have a rough surface that helps to disturb the boundary layer. Adding surface irregularities that are too large causes areas with little air flow.

The trade off is fewer fins require thicker fins to better conduct the heat in the metal as each fin has to carry more heat. Thinner fins each carry less heat, so they don't need as much air to carry the heat off each fin, so more narrow spacing works well. Bottom line is, one limitation in the heat flow is the surface area. Rough, smooth, wavy, whatever. It needs enough surface to transfer the heat by contact. Generally, more is better since this is a point of very low conductivity, high resistance per unit area.

The boundary layer is the the layer in which local airflow gets faster. It gets narrower as the airspeed away from surface get faster. It's - very roughly - about 5mm thick at the sort of air velocities of interest here.

With skived fins the airflow between the fins is never going to be fast enough to be turbulent, and the air flow is going to be smooth, slow and laminar.

True, but if you can't get much airflow, you can't carry off much heat. Skived fins offer more surface area than the solid aluminium block they were skived off, but it's hard to get much airflow between them. Free convention would be a lot better than it would be a for the original sold block, but forced convection would need high air pressure to get much extra flow.

A wavy fin would be messy to skive. The right angle at the root of each blade would be wavy too. I'd expect things to break.

The process is crazy enough already!

Why the device in the image is any better than air cooling. Since it is still air cooling, but 6 inches away.

I refuse to answer you twice. See above.

Only for those who lack imagination. For the retarded, here's a little picture for you....

All cars are air cooled, what do you think that fan at the front does?

Do the colored LEDs improve heat transfer?

If you don't want to converse, what are you after?

It cools better in the sense of moving more heat with a lower temperature delta. What part of this do you not understand? Do you think every combination of heat sink and fan works the same?

I never connected mine, and it seems to be ok. I guess it could be an indicator the fans are operating.

I did converse, did you not read the other line only two lines up? I simply objected to you repeating yourself.

It moves as much heat as the fan speed and heatsink surface area allow. Moving this further away serves no purpose apart from introducing another "resistance" in the heat movement.

They look fine to me. Assuming the use is in something like a 1U server, that style works fine to over 200 watts per heatsink that's less than

Blowing air at 90 degrees into a heatsink is some 1990s nonsense.

Current server designs have far simple air paths than old machines, and even dissipate more power. The days of the pop can sized heatsinks on stuff like a PA-RISC processor is long over. Getting heat out of the die and package is part of the problem due to size these days. Certains parts of a processor can be hitting thermal limits while other parts nearby are just fine. It's sort of bizarre actually.

The real magic seems to be in the fans that are available now. They're real powerful, real small and the top shelf ones last a really really long time.

I have seen many radiators in AC conditioners that are almost paper thin (or razor blade thin, if you prefer), and they are very easy to damage. In fact, they often were already damaged and sections of the units were not working because being bent against one another they blocked the air flow.

You can't mount such large fans on a heat sink bolted to the CPU. Well, I shouldn't say "can't", but it's not recommended. At some point there is not sufficient strength to support such a large mass on such a long lever arm.

I'm sure you will find some insane heat sink somewhere. Whatever. This is the reason for water cooling. To get a lower temperature at the CPU than you can get with an attached heat sink and fan.

As I've pointed out, with some water cooling setups, you don't even need a fan, just a pump which is much, much quieter and that can be in another room. The one guy put his in the garage. No fan, no radiator, just a barrel and a pump.

I have two 6 inch fans on mine. That's no less than on water coolers for CPUs.

You don't need a lower temperature. They're rated up to about 90C.

Those make sense. I used to have one. Big water tower behind my desk.

Someone I know on the Boinc projects has several GPUs water cooled by a domestic central heating radiator, which is outside his house. Could be inside, but he lives in a hot place.

I don't care about your 6 inches. The water cooler is a more effective cooler and lowers the CPU temperature. Why can't you understand that?

LOL!!!! You have no understanding of why people by aftermarket CPU cooling. So there's literally no point in this discussion.

Why? The CPU is happy at 90°C!

What a tool. Like the other discussion, there's no point in continuing. I think you are a self contradiction.

Gamer PCs and keyboards are always funny. I remember when cars had tail fins and jeans had bell bottoms.