With the arrival of the 12th Gen Intel Core processors codenamed Alder Lake, we expect to see lots of new technologies crammed into one package. Today, according to a Coreboot patch (via Coelacanth’s Dream), we see some first-hand information about different power states and Power Limit 4 (PL4) levels of the upcoming Alder Lake-M and Alder Lake-P designs.
Coreboot is an open-source solution designed to replace millions of proprietary BIOS implementations. The project aims to boot 32-bit and 64-bit operating systems on bare metal (aka the hardware) with minimal functionalities, making it a lightweight BIOS alternative. Today, the latest patch to this software project has brought us some information regarding Power Limit 4 (PL4) for Alder Lake P/M processors, which differs from the previous generation, Tiger Lake, that it is replacing.
The new information regards the two Alder Lake processor families, shown on the Brya platform, which is a reference validation platform for Chromebooks. One is for Alder Lake-M, which is a super low-power range of CPUs designed for 5-7W TDP in this case, while the other is for Alder Lake-P, which represents processors with 15 Watt TDP. There are other power envelopes in the M and P brackets, mind you, so they aren't shown here.
For perspective, PL4 is the absolute maximum power limit that the SoC could sustain without damaging itself. It is an impermanent power value that the CPU avoids at all costs, capable to last for only a short period before the CPU shuts down. Before PL4, there are other levels like PL1, representing your processor TDP, PL2, that is maximum boost frequency level, and PL3, which throttles the CPU a bit to remain usable, while the PL4 function severely throttles the CPU even before it encounters the defined limit.
In the table below, you can note the values for the Alder Lake processor compared to the previous generation Tiger Lake designs. Note that there are four SKUs present: Alder Lake-P (2+8+2), Alder Lake-P (4+8+2), Alder Lake-P (6+8+2), and Alder Lake-M (2+8+2). Each number represents the number of big cores, small cores, and levels of the integrated graphics, respectively. In this case, the GPU is GT2 level, which is a configuration with 96 Execution Units (EUs).
| Header Cell - Column 0 | Tiger Lake-U | Tiger Lake-H | Alder Lake-P | Alder Lake-M |
|---|---|---|---|---|
| PL1 | UP3: <= 28W UP4: <= 9W | <= 45W | (2 + 8 + 2): <= 15W | (4 + 8 + 2): <= 28W | (6 + 8 + 2): <= 45W | (2 + 8 + 2): <= 9W |
| PL2 | UP3: <= 38W (2C), <= 60W (4C) | UP4: <= 35W (2C), <= 40W (4C) | 107 - 135W | (2 + 8 + 2): <= 55W | (4 + 8 + 2): <= 64W | (6 + 8 + 2): <= 115W | (2 + 8 + 2): <= 30W |
| PL4 | UP3: <= 71W (2C), <= 105W (4C) | UP4: <= 66W (2C), <= 83W (4C) | Row 2 - Cell 2 | (2 + 8 + 2): <= 123W | (4 + 8 + 2): <= 140W | (6 + 8 + 2): <= 215W | (2 + 8 + 2): <= 68W |
As you can note, the Alder Lake-P PL4 values can go as high as 215 Watts in the shown configurations. This is not representative of all SKUs, as some could be potentially even higher. For Alder Lake-M, it goes "only" up to 68 Watts. These values should not be exceeded more than 10ms, as the laptop's battery and charger are not designed to handle it for longer periods. Hence the PL4 limit.
Add this little brick of information to the wall of information that suggests we are on the cusp of the imminent Alder Lake launch.
