Question different CPU lids?

[MeeLee]

Why do major CPU companies, instead of using the standard CPU lids, not use larger size copper lids, that are about the size of the bottom of the CPU?
A larger surface, better thermal heat dissipation, all seem to start making more sense now that we're running Cooling solutions that have larger base plates than the entire CPU together?

 

[COLGeek]

Nickel plated copper is what is commonly used. Makes the IHS more durable as pure copper can be quite soft if not alloyed. Cost would also be a factor.

 

[Newtonius]

Yep, as @COLGeek said, it costs more. Copper is more expensive than the material already used in IHS (the lids). It used to be that the die of the CPU itself was exposed but because people would accidentally crack the Die when mounting heatsinks they decided to put an IHS on them to prevent this - and when manufacturing millions of these when they're simply a safety measure, cutting costs is ideal as long as it still does its job.

 

[USAFRet]

Effectiveness.
Having a lid larger than the actual part that generates the heat does not automatically mean better heat distribution/dissipation.

 

[COLGeek]

Back in the day, you could buy copper shims to help with heat management of particular CPUs. Part of this was influenced by the lack of precision tooling to make the heatsinks we have today. Previous CPU design, as mentioned earlier, was also a concern and the shims could help with that, too.

 

[MeeLee]

Effectiveness.
Having a lid larger than the actual part that generates the heat does not automatically mean better heat distribution/dissipation.

Yes it does.
The lid is what subtracts the heat from the CPU die itself, and making it larger increases the surface area. This means that heat will be subtracted along the lid as well as through the lid.
Of course, if your heat sink surface area touching the lid is smaller than the lid, it won't do much in terms of heat dissipation, but if the heatsink block covers the area of the lid, it'll definitely subtract more heat!

 

[USAFRet]

Yes it does.
The lid is what subtracts the heat from the CPU die itself, and making it larger increases the surface area. This means that heat will be subtracted along the lid as well as through the lid.
Of course, if your heat sink surface area touching the lid is smaller than the lid, it won't do much in terms of heat dissipation, but if the heatsink block covers the area of the lid, it'll definitely subtract more heat!

It may...not automatically does.

If it were needed, and if it were cost effective, and if it could be designed to not allow off-angle stress on the die...it would be a thing.

"Why does this not exist?" leads to "Does it need to exist?"

Since the current crop of CPU's seem to run just fine with current coolers and the size of the lid...reducing the temps is not going to make them run any faster.

 

[geofelt]

A lid is currently larger than the top of the cpu chip itself.
The primary heat exchange is between the top of the chip and the lid.
The closer to a metal to metal contact, the better.
That is why there can be a benefit of "delidding" a processor.
No doubt there is some heat generated from the rest of the processor assembly, but that does not warrant a much larger lid.
I Think a lid could be about as effective if it were smaller, covering just the cpu chip, but from a practical point of view it is about the size of the total processor assembly.
Making it larger than necessary would have an impact on motherboard design where size and spacing are critical.

Probably not worth second guessing the Intel engineers.

 

[COLGeek]

The "lid" also helps distribute weight and protects the CPU itself. De-lidding is not without significant risk.

 

[MeeLee]

The lid is indeed smaller than the CPU die, however the sides of the lid are considerably hotter than the top (contact area with the heat sink)..
This means that a larger lid, will certainly give more cooling.
Especially if in the near future CPUs will have some sort of thermally conductive, electrically insulating substances in them for improved heat flow.

But anyway, the bottom of the CPU is larger than the CPU lid.
And as much heat gets dissipated on top, as is on the bottom (as CPUs have thermally conductive pins connecting them to the CPU die).
So I would say 'definitely, a larger lid, will definitely lower cooling'.

And cooler CPUs in many cases DO run faster (seeing that most modern CPUs come with thermally regulated turbo boost frequencies).

 

[MeeLee]

Nevermind,
The current lids for AMD Ryzen CPUs are about as big as the socket clap can hold. I don't know about Intel, but AMD maxed out their design, resulting in much better cooling, making the question solved...

Ow and larger lids definitely DO make for better thermal conductivity!

There's only one way to get better, and that's making them so large that one will have to get rid of the CPU clamp.

 

[CountMike]

Nevermind,
The current lids for AMD Ryzen CPUs are about as big as the socket clap can hold. I don't know about Intel, but AMD maxed out their design, resulting in much better cooling, making the question solved...

Ow and larger lids definitely DO make for better thermal conductivity!

There's only one way to get better, and that's making them so large that one will have to get rid of the CPU clamp.

It's not lid size or even material that made Ryzen transfer heat better and faster but the fact that core chips are soldered using metal compound while some other CPUs use use just heat transfer paste not better than paste used between lid and cooler. That's where "deliding" comes into effect, paste is replaced by liquid metal like Cryonout which does better job, doesn't mean that lid is kept off. There are also available lids made of silver which is even better heat conductor.
As there is most heat transfer at point of core chip surface and lid just on that point, some CPU cooler manufacturers made contact surface a bit convex so most pressure is located at center making closer contact. CPU lid may also be slightly convex for same reason.
Other options are to send and burnish both surfaces flat and as smooth as possible.

 

[MeeLee]

The soldered lids, is totally besides the point.

 

[drea.drechsler]

.

Nevermind,
The current lids for AMD Ryzen CPUs are about as big as the socket clap can hold. I don't know about Intel, but AMD maxed out their design, resulting in much better cooling, making the question solved...

Ow and larger lids definitely DO make for better thermal conductivity!

There's only one way to get better, and that's making them so large that one will have to get rid of the CPU clamp.

Can't move the heat out of the CPU to the heat spreader any faster than the surface area of the die allows. A bigger spreader helps only if the die contacts an equally larger area of the surface underneath the spreader. AMD's 7nm dies are very small so that makes them hard to cool. The spreader's as big as it is to fit three dies (2 CPU chiplets and one IO chiplet) and associated circuitry (lots of MLCC's under there too) underneath it. .

The only other way to improve it is to increase the temperature differential between the spreader and die with better cooling.

Direct die heatsink mounting is also a way to get it better cooling. GPU's use direct die, but cooler attachment can be tricky and lots of people have bricked their GPU's in the process of renewing old thermal paste. AMD tried it back in the K7 and Thunderbird days with lots of chipped CPU die corners resulting.

Der8auer's done some cool testing with re-centering an AIO's waterblock directly over the CPU dies of a Ryzen 3000 CPU and actually demonstrated some minor, but measurable and repeatable, temperature improvement. That clearly suggests simply enlarging the spreader won't help.