Intel 12th Gen Alder Lake Mobile CPU Power Limits Revealed In Coreboot Update
A recent Coreboot patch for a Chromebook development device featuring Alder Lake inside (codenamed "Brya") appears to have outlined some of the power limits of Intel's next-generation mobile processors. Included in the patch notes are PL1, PL2, and PL4 wattage ratings for Intel's Alder Lake-P and Alder Lake-M CPUs.
Alder Lake-P and Alder Lake-M comprise Intel's upcoming 12th Gen mobile CPUs that will feature the same hybrid (or heterogeneous) architecture as its next-gen desktop CPUs that are due out later this year. The same package will contain two sets of cores—high performing Golden Cove cores and more power efficient Gracemont cores.
Intel will embrace its hybrid architecture on both the desktop and in mobile, though the latter is where the efficiency gains could potentially have a bigger impact. One needs only to look at the smartphone and tablet landscape, where Arm's own hybrid designs (dubbed big.LITTLE) dominate the field. We'll soon see how this approach works when fully embraced in x86 computing.
As to the leaked power limits, here's how it works out...
Hat tip to Coelaceanth's Dream for spotting and digging into the Coreboot patch notes, and aligning them with Tiger Lake. In doing so, we see Alder Lake-P and Alder Lake-M aligning quite nice with Tiger Lake-U and Tiger Lake-H.
The numbers in parenthesis for Alder Lake indicate the number of big (Golden Cove) cores, small (Gracemont) cores, and the integrated graphics level (GT2 across the board, it appears)..
According to the chart, Alder Lake-M spans 9W (PL1), 30W (PL2), and 68W (PL4), while the starting values for Alder Lake-P are 15W (PL1), 55W (PL2), and 123W (PL4). At the higher end, Alder Lake-P has up to a 215W PL4 power rating, for a 14-core/20-thread configuration.
Bear in mind that PL4 rating only apply to extremely short bursts in clock speed, up to just 10 milliseconds. Compared to Tiger Lake, Alder Lake's peak values represented by PL1 and PL2 are similar, though these values could also be different in other types of laptops (read: non-Chromebooks).
It remains to be seen when Alder Lake in mobile form will arrive. Intel is still on track to launch Alder Lake before the end of the year, though rumor has it we will only see a few high-end desktop processors at launch, followed by other Alder Lake CPUs next year.
