Speculation and Rumors: AMD RDNA4 ...

Just "Moar chiplets!", that texturing unit RT traversal acceleration patent AMD hasn't done anything with yet, and the assumption that it will be on TSMC 3(?)nm.

Oh, and likely 2024 release date.

Moar chiplets as in multiple compute die will likely show up on CDNA before it shows up in RDNA.
 
Got it. Consoles are the devil. NV is a saint. Amd+Intel are accepted.

Now that attitude is defined and agreed, let's get started with the rumors.
For a little while at least. :D

Not what i ment, i said both ways. Keep it to rdna4 without the involvment of consoles and there will be less noise, less indirect amd vs intel vs nv attacks.
 
Are there any for this yet?
Here's a speculation: They'll go full chiplet, i.e. with multiple GCD as well. Hopefully, they'll have figured out how to present two GCDs as one single device to the driver. Unlike MI250X, which is two separate OpenCL devices.

If they pull that successfully off, it'll become clear why chiplets are a huge advantage. If they'll stick with another round of MCDs attached, then it might become difficult to sustain the edge, since chiplets is a one-off advantage until the others have followed suit.
 
Hopefully, they'll have figured out how to present two GCDs as one single device to the driver. Unlike MI250X, which is two separate OpenCL devices.
I guess that's possible, e.g. by having some sub command processor per compute tile, with one main processor on the top. Not much new data flow besides the commands seems needed across the tiles then?

But initially i had assumed chiplets means the same revolution which happened to CPUs when going multi core, so we would see indeed multiple small GPUs.
Harder to saturate, but not impossible. I would still prefer it if it helps with pricing. I don't think this would be as disruptive as many people think. You still have only one VRam for all GPUs, and driver can help with translation of old games.

Though, it's still a revolution. AMDs market share is too small to establish this, and single device is their only option. Maybe this adds some thing to the respect they deserve for pioneering chiplets.
 
But initially i had assumed chiplets means the same revolution which happened to CPUs when going multi core, so we would see indeed multiple small GPUs.
Windows doesn't have any kind of NUMA system for GPUs though, that's the big difference.
 
If they pull that successfully off, it'll become clear why chiplets are a huge advantage. If they'll stick with another round of MCDs attached, then it might become difficult to sustain the edge, since chiplets is a one-off advantage until the others have followed suit.
I don't see chiplets ever being more than a one-off advantage, whichever variants of "chiplet" and "stacking" are involved, and however many stages of evolution they go through for GPUs, specifically.

There's no reason to expect NVidia to be more than one generation late with chiplets - it was one generation later with a monster on-die cache.

Maybe RDNA 4 is where this happens:
b3da048.png



So we have:
  • active interposer die (AID) - graphics control processor and last level cache
  • shader engine die (SED) - corresponds with shader engines seen in current RDNA GPUs
  • multimedia and I/O die (MID) - crap that belongs on a cheap process.
There is no GCD as such in this design.
 
Maybe solutions with 4 "GCD" (shader dies?) at the top range, then lower ranges could use 3 or 2, while lowest end could be still monolithic.
It would be interesting to know if the memory interconnection will be something like RDNA3 (most probable) or another new solution.
 
Last edited:
… however you may call those and whereever you draw the line between one (GDC) and the other („graphics processing stacked die chiplet“).
As I understand it, the big difference is that GCD contains the command processor, while the SED is just arrays of shaders, and command processor is on the base die.

This patent is different from the earlier AMD stacked GPU one in that memory controllers are moved form the SEDs to the base die with the cache, and instead of having different size base dies for different products, they appear to be making one design and then connecting them with stacked bridge chips.

I like the design. It requires a ridiculous level of confidence in the hybrid stacking process, but if there's one company on the planet that can build that confidence, it's probably AMD.

There's of course the obligatory caveat that just because a company patents something doesn't mean that they are building it any time soon, or ever.
 
Back
Top