Ryzen Watch Out! - Intel's i9-13900K CPU has been spotted with 68MB of Cache
Will these cache improvements give Raptor Lake a gaming boost?
Published: 18th May 2022 | Source: @OneRaichu - Twitter |
Intel's Raptor Lake processors are getting a major cache upgrade
Rumour has it that Intel's 13th generation Raptor Lake processors will feature some significant cache upgrades over today's 12th Generation Alder Lake models, and @OneRaichi has released some new evidence that supports this claim in the form of an alleged i9-13900K CPU-Z screenshot.
In total, Intel's i9-13900K has been listed with 36MB of L3 Cache and 32MB of L2 cache, giving the CPU 68MB of combine L2/L3 cache. For context, Intel's i9-12900K had 30MB of L3 cache and 14MB of L2 cache, giving the i9-12900K a total of 44MB of L2/L3 cache. This gives the i9-13900K 24MB more L2/L3 cache, and that's a big deal.
Raptor Lake's L3 cache has not changed much
With Raptor Lake, Intel reportedly offering processors with eight P-cores (Performance Cores) and four clusters of E-Cores (Efficient cores), each of which contains four E-cores (for 16 total E-Cores). Intel's P-Cores come with 3MB of L3 cache each, and Intel's E-core clusters come with 3MB of L3 cache each.
The addition of two more E-core clusters with Raptor Lake adds 6MB (2x 3MB) of additional L3 cache to Intel's Raptor Lake i9-13900K. This gives Raptor Lake a total of 36MB of L3 Cache. With Raptor Lake, Intel is not adding additional L3 cache per CPU core/core cluster, they are simply adding more E-Cores. That said, L3 cache is accessible by all cores, which makes this added cache very useful for some workloads.
L2 Cache - Where the real upgrade happens
With Raptor Lake, Intel has making some major upgrades to their L2 cache structures, both on the P-cores and E-cores. On their P-cores, they are upgrading Alder Lake 1.25MB L2 cache to a 2MB L2 cache for Raptor Lake. This is a 60% increase in L2 cache size, allowing each core to store more data on their low latency L2 cache. This cache decreases strain on Raptor Lake's L3 cache, making it more effective.
On Raptor Lake's E-cores, Intel is upgrading their 2MB L2 cache, which is split between four E-cores, to a larger 4MB L2 cache. This doubles the size of the L2 cache that E-cores have access to. This again allows these cores to store more data on this near-core cache, again reducing strain on higher up areas of Intel's cache structure.
(Intel Raptor Lake Cache visualisation - from @Olrak29_)
Why these cache upgrade matter
Simply put, if cache sizes did not matter, Intel wouldn't have upgraded their cache sizes with Alder Lake and upgraded them again with Raptor Lake. Larger caches allows Intel's CPUs to store more data on their chips, data which can be access more quickly and efficiently by their CPU cores.
The reason why CPUs have cache is because DRAM is slow, at least when compared with cache. L1 cache is faster and less latent than L2 cache, L2 cache is less faster/less latent than L3 cache, and L3 cache is much faster and less latent than DRAM. Having larger caches can have latency consequences, which is why L1 caches are often very small. With larger L2 and L3 caches, the hope is that Intel's Raptor Lake processors will be able to spend less time waiting and more time working.
A larger L2 cache will reduce the strain on Intel's L3 cache and accelerate some workloads, and Intel's enlarged and alleviated L3 cache will be able to store more data and allow Raptor Lake processors to spend less time waiting on DRAM. If workloads function well with these new cache sizes, Raptor Lake could deliver significant performance gains for Intel. This may be especially true for gaming workloads, which can be very cache/memory sensitive.