Shut-up photographs of AMD’s RX 7900 XT (opens in new tab) have revealed what seem like connection factors used with 3D chip stacking applied sciences. Engineer Tom Wassick has zoomed in on the reminiscence chiplets inside the Navi 31 GPU, referred to as MCDs, and what he is discovered are tiny “spots” that seem just like these on AMD’s V-Cache CPUs.
Based on Wassick (through Tom’s Hardware (opens in new tab)), who has seen AMD’s newest GPU with an infrared digital camera, these spots might present a latent capacity within the RDNA 3 GPU that will permit AMD to stack one other chip on prime of the MCD.
What else are you able to see? A linear array of “spots” that look remarkably just like the preserve out zones on X3D, and which are on the identical 17-18 um pitch. May they be contemplating stacked MCD performance (or possibly they’re one thing else)?January 27, 2023
It was rumoured again within the growth course of for the Navi 31 GPU that AMD would implement stacked MCDs, however reportedly determined in opposition to it, at the least for the primary chips. There have been rumours of a Navi 31 refresh later within the 12 months, however equally contrasting rumours claiming such a refresh has been canned (opens in new tab). Having the potential for drastically rising the accessible cache for the RX 7900-series playing cards would have been a robust device to have within the AMD arsenal for any potential later replace.
These connection factors might then both be legacy connections from older plans for the GPU reminiscence dies, or paving the best way for a future improve. How that would take form, if it ever does, stays a thriller, however in concept a GPU may benefit from having extra reminiscence shut at hand as a lot as a CPU.
AMD has discovered further efficiency from bumping up the cache capability on each its newest GPUs and CPUs. The Infinity Cache launched with the Ryzen 6000-series graphics playing cards helped improve its accessible reminiscence bandwidth, and the primary processor with 3D V-Cache expertise, the Ryzen 7 5800X3D (opens in new tab), runs considerably quicker than the Ryzen 7 5800X in cache-heavy workloads (i.e. gaming). That very same kind of efficiency uplift can be anticipated for the upcoming Ryzen 7000-series V-Cache (opens in new tab) chips, that are making ready for battle in opposition to Intel’s Raptor Lake processors someday in February. Whereas right this moment’s Ryzen 7000-series tends to lose that battle, the 3D V-Cache chips are anticipated to be far more aggressive, possibly even topping the efficiency charts.
Nvidia has additionally adopted AMD’s lead, massively rising the L2 cache on its Ada Lovelace-based graphics playing cards of the RTX 40-series. Little question AMD will likely be trying to different implementations of the expertise to as soon as once more maximise efficiency itself.
Each the RX 7900 XT and RX 7900 XTX (opens in new tab) include a chiplet-based GPU, and that can play a key function if AMD does look to bolster cache quantities on its GPU with chip stacking tech.
The Navi 31 GPU is cut up into two element elements: the GCD and MCD. There are six MCDs on the XTX and 5 on the XT, although it seems the identical because the XTX because of a dummy block of silicon changing the sixth MCD. In concept, AMD might scale up the reminiscence chiplet rely with 3D V-Cache, all with out increasing the GPU’s general footprint.
Alas, that is solely a dream, although the telltale indicators of chip-stacking capabilities would possibly trace at what’s to return from the purple crew. For now, we’re hoping for a swift launch of some cheaper graphics playing cards out of the RDNA 3 structure, however preserve your eyes on the horizon for a chiplet-based, 3D-stacked behemoth. We will solely hope that is one thing the purple crew’s contemplating, and never one thing it is already canned.
