Macs getting hot when doing normal office works

I have 4 old Macs at home and decided to install OCLP/Sonoma on 2 of them as I’ve become more and more frustrated with the increase of apps dropping compatibility on the older systems recently. I did clean installs in both cases and did the post-install configs as per the guides, I also turned off the fancy backgrounds.

Both macs work without major issues, the older one is a bit slower than before but still acceptable. However, both of them get very hot with simple tasks (office works, couple of windows open: Safari, Mail, excel, messengers etc).

I checked the activity monitor and haven’t found any tasks consuming a lot of CPU %, do you have any idea how to further battle the temperature issue or is it just the computer not being compatible with modern systems any more that require more GPU/CPU to run cold?

The Macs have had thermal paste replaced this year and used to work much colder before the system update.

• A1278 MacBook Pro i7, 2012 (SSD, 16gb RAM)
• A1398 MacBook Pro Retina 2015 (SSD, 16gb ram)