One of the differences between desktop/laptop CPU design and the ARM CPUs used in mobile devices is that the latter rely on a scheme known as big.Little. Because mobile devices have such small power envelopes, their SoCs often have two sets of cores — a “big,” powerful set of CPU cores to handle intensive workloads, and a set of “little” cores to handle basic, low-power tasks. Apple doesn’t call its own approach big.Little, but it operates on the same principle.
AMD and Intel, in contrast, have never adopted a big.Little configuration for any desktop CPU.
The closest part to exist on the x86 side of things is Intel’s Lakefield, which combines four Atom-class CPU cores with a single 10nm Ice Lake core. If these rumors are accurate, that’s going to change with Alder Lake-S. Not only will Intel be bringing a big.Little configuration to market, it’ll do so in high-wattage CPUs.
The rumor concerns a slide, purportedly by Intel, showing the company launching an Alder Lake configuration with eight big cores and eight little ones, paired with a “GT1” graphics processor on LGA 1700.
We always say to take rumors with a grain of salt, but I’d take this one with a shaker. The socket timing isn’t crazy, especially if Intel maintains heatsink compatibility. The idea of a “GT1” graphics core would imply that Intel is rebranding its GPU division, since desktop chips have typically carried GT2, but that’s not impossible either.
The technical reason to be wary of this rumor is that it’s not at all clear why you’d want to bring an 8+8 configuration to a desktop chip. Windows 10 was updated to support big.Little as part of making it ARM compatible, but most desktop users would prefer to just have either 1). More clock frequency or 2). More “big” cores if offered a choice. Benchmarks of big.Little SoCs that date to 2015 show that the advantage of firing up the little cores was relatively small:
It is always possible that Intel has found a method of improving performance from simultaneous workload execution or that the little cores are intended to operate in a low-power idle mode that cuts desktop power consumption significantly while keeping the system responsive. But while desktop users can and do care about power efficiency, this seems much more like a mobile feature than a desktop one. The specific rumor here is about desktop, not notebook.
Could this be an attempt by Intel to “fake” having a 16-core CPU for desktops? Again, possible, but not particularly likely. Such a shift would be spectacularly poorly received by the press and it’s not clear what kind of benefit Intel gets from doing this in the first place.
Finally, there’s the fact that Intel will already have 10-core CPUs in-market with Comet Lake this year. Now, Intel can and does make modifications to its CPU families — it has added and removed Hyper-Threading, for example, and increased the absolute number of cores available in the i3/i5/i7 families. But falling backward on Alder Lake from 10 to 8 would be an unprecedented reduction. Intel would need to be confident in a significantly higher IPC and/or clock speed in order to be able to be certain that 8 CPU cores would outperform 10 from a previous generation.
Then again, if Intel could take its 1.18x IPC increase from Ice Lake over Coffee Lake and combine it with Coffee Lake’s frequency scaling, that would represent a 1.16x improvement in performance right there. So, again, there’s a potential path here, particularly if Intel relaxed its TDP to 150W — but there are also reasons to question whether the company would implement this kind of strategy, and more questions than answers about the advantages of doing so.
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