Hi,
After searching around I found a blog here which listed the steps to get System Temp Running.
I'll place a bit more instructions here though for anyone else looking:
Install Nerd Tools following the post here
Install Perl by opening the Nerd Tools plugin and selecting the slider
Open the System Temp Plugin
The detect button should be active now, so press it and save
Select the applicable sensors
Press Apply
Press Done
You can uninstall Perl by going back to the Nerd Tools plugin
Grab a drink and stay cool
P.S.
Also found author's instructions here ?
