2018-03-30, 14:06 PM

As described here, in Linux only on my T480s (8550u, bios 1.11) the cTDP value is set to a value much lower than in Windows (wich is 44W). Specifically, I found that the PKG_POWER_LIMIT is configured correctly, but the corresponding register in the MCHBAR is not and the latter overrides the former.

The second issue is related to a lower thermal trip point w.r.t. Windows: the value 0x14 is set in the MSR_TEMPERATURE_TARGET, causing CPU throttling as soon as 80 C are reached, while on Windows the processor is throttling at about 97 C. Moreover, the EC seems to overwrite this MSR periodically to its default value.

These two issues combined cause Linux performance to be almost halved w.r.t. Windows during heavy load. Other users have reported the same problem in X1C6 and T480.