News AMD 3D V-Cache teardown suggests the majority of the Ryzen 7 9800X3D is occupied by dummy silicon

[Admin]

An in-depth analysis of the Ryzen 7 9800X3D suggests that a large portion of the chip is comprised of structural silicon.

AMD 3D V-Cache teardown suggests the majority of the Ryzen 7 9800X3D is occupied by dummy silicon : Read more

 

[chaz_music]

Don't forget that the added silicon also helps add thermal mass to the entire chip system, giving better transient thermal behavior. That thermal mass slows down the thermal time constant and give the power control system more time to react within the system during heavy loading. So it isn't all wasted silicon just for mechanical reasons.

 

[gjonezin]

Don't forget that the added silicon also helps add thermal mass to the entire chip system, giving better transient thermal behavior. That thermal mass slows down the thermal time constant and give the power control system more time to react within the system during heavy loading. So it isn't all wasted silicon just for mechanical reasons.

This makes sense. My first thought was, "you mean they have room to add MORE Vcache?!"

 

[HardwiredWireless]

Don't forget that the added silicon also helps add thermal mass to the entire chip system, giving better transient thermal behavior. That thermal mass slows down the thermal time constant and give the power control system more time to react within the system during heavy loading. So it isn't all wasted silicon just for mechanical reasons.

You say 'don't forget' as if you are retelling what was proven in the analysis, but that was never shown. It's interesting but there's no evidence that is happening or could happen with the layout being what it is.

 

[edzieba]

Don't forget that the added silicon also helps add thermal mass to the entire chip system, giving better transient thermal behavior. That thermal mass slows down the thermal time constant and give the power control system more time to react within the system during heavy loading. So it isn't all wasted silicon just for mechanical reasons.

The cache die is on the opposite side of the compute die from the HSF. Any heat the cache die absorbs can only leave by heating up the compute die again.

 

[Phyzzi]

It would be pretty incredible if we got to the point of adding diamond instead of non-computing silicon to these chips for structure and thermal sink. I assume that some of the chip is being built by vapor deposition anyway, and doing it with or on diamond could certainly improve performance.

 

[mwestall]

An in-depth analysis of the Ryzen 7 9800X3D suggests that a large portion of the chip is comprised of structural silicon.

AMD 3D V-Cache teardown suggests the majority of the Ryzen 7 9800X3D is occupied by dummy silicon : Read more

For heavens sake guys:-
"Ryzen 7000 3D V-Cache chiplets measured 36mm-squared"
No no no no no no no.
It's 36 **square mm** 36mm squared is 1296 sq mm.

 

[NinoPino]

The cache die is on the opposite side of the compute die from the HSF. Any heat the cache die absorbs can only leave by heating up the compute die again.

Right, but it could help to transfer heat from the die hotspots, to the near area, distributing the heat homogeneously on all the die.

 

[bit_user]

The thickness of the entire package is roughly in the ballpark of 800µm. Subtracting the 50µm die stack (CCD, SRAM, and BEOL) lands us at 750µm of structural support at the top. In other words, 93% of the total stack comprises just dummy Silicon to keep the dies intact.

Why are you so sure it's all just for structural support? Maybe the reason it's that thick is to reduce the gap between the compute die and heat spreader?

 

[bit_user]

The cache die is on the opposite side of the compute die from the HSF. Any heat the cache die absorbs can only leave by heating up the compute die again.

That's silly. CPUs do indeed transfer a non-trivial amount of heat through their pins, into the motherboard. Even though the bulk of it normally goes through the IHS, try pointing an IR thermometer at the backside of your motherboard, under the CPU socket. Heat definitely manages to transfer through the socket, into the motherboard.

What @chaz_music said seems plausible to me. To go further down this path, we'd need data on the thermal mass of that base layer and the thermal conductivity of the SRAM die. Since the SRAM die is so thin, I doubt it's providing much thermal resistance.

 

[oofdragon]

Dummy silicon > Intel 😂😂😂

 

[Kondamin]

Nice, replace it with gdram for the igpu

 

[NinoPino]

Nice, replace it with gdram for the igpu

Nice point, and I also wonder why AMD don't release a double cache version of 9950 with 3Dcache on both CCDs.
I suppose there are limitations on the TSV or power/heat dissipation.

 

[HardwiredWireless]

When you are making silicon to sell to dummies it makes sense to sell dummy silicon. 🤭

 

[Pierce2623]

For heavens sake guys:-
"Ryzen 7000 3D V-Cache chiplets measured 36mm-squared"
No no no no no no no.
It's 36 **square mm** 36mm squared is 1296 sq mm.

Somebody can’t tell the difference between the word “squared” refusing to a shape or a mathematical function. “36mm squared” is absolutely 100% correct English parlance for a square with 36mm sides.

 

[bill001g]

Somebody can’t tell the difference between the word “squared” refusing to a shape or a mathematical function. “36mm squared” is absolutely 100% correct English parlance for a square with 36mm sides.

This is what happens when you have someone whose primary job is journalism and not math/science. In addition the original data was not written in english so it might have been machine translated. The person writing or translating the article should have noticed that this was a confusing way to state this.