AMD Infinity Cache Explained : L3 Cache Comes To The GPU!

Infinity Cache is a brand new feature being introduced in the new Radeon RX 6000 Series graphics cards.

Find out what Infinity Cache does, and how much of an effect it has on gaming performance!


AMD Infinity Cache : Part Of RDNA2 Architecture

The new AMD RDNA 2 architecture introduces an enhanced compute unit, a new visual pipeline, and the all-new AMD Infinity Cache.

Thanks to these new features, RDNA 2 promises to deliver up to 54% better performance per watt over the last-generation RDNA, and up to 2.17X more bandwidth with its new Infinity Cache.


AMD Infinity Cache : L3 Cache Comes To The GPU!

AMD Radeon GPUs based on GCN and RDNA architectures have both L1 and L2 caches to keep the compute cores “fed” with data.

In the last-generation RDNA architecture, the per-core L1 cache was combined into a new 128 KB L1 cache that is shared by two Compute Units.

The 4 MB graphics L2 cache is shared globally by all of the Compute Units in the GPU.

In the new RDNA 2 architecture, AMD added Infinity Cache – a 128 MB on-die cache. This is obviously a very large L3 cache.

Even their recently announced Ryzen 9 5950X and Ryzen 9 5900X processors only come with 64 MB L3 caches.

While common in modern CPUs, this is probably the first time an L3 cache is used in a GPU.

The new NVIDIA Ampere, in comparison, uses larger L2 caches instead – 40 MB in the A100 and 6 MB in the GA102.


AMD Infinity Cache : Performance Implications

When AMD revealed the Radeon RTX 6000 series, many people noticed that all three cards only came with a 256-bit memory interface and still use GDDR6 memory.

That’s hardly competitive against the NVIDIA GeForce RTX 30 Series graphics cards, with their GDDR6X memory and much wider 384-bit and 320-bit memory interfaces.

That’s where Infinity Cache comes in – it lets AMD double the memory bandwidth and reduce power consumption, while using a narrower 256-bit interface and slower GDDR6 memory.

Of the 54% boost in performance-per-watt AMD reported, it appears that more than a third of that improvement can be attributed to Infinity Cache.

Do note though that AMD is talking about performance-per-watt, not performance improvement per se.

Keeping that in mind, AMD says RDNA 2 offers twice the performance of the last-generation RDNA architecture, represented here by the Radeon RX 5700 XT.

While AMD has not shared exactly how much that performance improvement is due to Infinity Cache, we have no doubt it will be substantial, especially in high memory bandwidth use cases like 4K gaming.

We will update this article when we learn more about AMD Infinity Cache, so check back for more information!


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