Same problem here:
Lenovo ThinkPad T410s Intel i5 (1st gen, 2.53Ghz) NVidia NVS3100M graphics
Kernel 4.4 in 16.04 idles at 35°C - 37°C (fresh, high-quality thermal paste applied a week ago).
Kernel 4.15 in 18.04 idles at 48°C - 52°C.
Only Dropbox and Megasync in the background; htop shows very low CPU use from these 2 apps.
Overall system CPU usage (idle) doesn't go above 1.3% - 2% range.
Same workflow from 16.04 + kernel 4.4 runs 20°C hotter in 18.04 + kernel 4.15.
Regular operation with Chromium and Emacs drives temperature to 76°C - 80°C.
Critical temperature is 95°C before shutdown.
This is running really hot.
Same problem here:
Lenovo ThinkPad T410s
Intel i5 (1st gen, 2.53Ghz)
NVidia NVS3100M graphics
Kernel 4.4 in 16.04 idles at 35°C - 37°C (fresh, high-quality thermal paste applied a week ago).
Kernel 4.15 in 18.04 idles at 48°C - 52°C.
Only Dropbox and Megasync in the background; htop shows very low CPU use from these 2 apps.
Overall system CPU usage (idle) doesn't go above 1.3% - 2% range.
Same workflow from 16.04 + kernel 4.4 runs 20°C hotter in 18.04 + kernel 4.15.
Regular operation with Chromium and Emacs drives temperature to 76°C - 80°C.
Critical temperature is 95°C before shutdown.
This is running really hot.