Which hard drive to keep

[jn110375]

hi i have a mac g4 osx 10.2.8 and added a 2nd hard drive from a mac g3 running on osx 10.3.9 they both run good except the fan got very allterated nonstop what should i do ?

 

[buwish]

Well, which out of the two is older and has had more use (if you know)?