I assume you are talking about the Stable version, in this version (and/or desktop) the cpu widget never worked as expected for some unknown reason. For that I suggest you to try the Beta version instead which improves this a lot (there's no widget, but there's a correct management of the cpu, you can configure it but manually on the /etc/laptop-mode files)
I also suggest you to try the Beta version because it includes many improvements in every sense, but the desktop experience is pretty different (the stable one looks better), also you must use the last (special version) build which has a lot of improvements in performance too, since this is important for your old machine: Elive Retro (Work in Progress) - #15 by Thanatermesis
