Dell Latitude 5480 fan suddenly and randomly becomes loud for a good amount of time and then becomes normal?

I’ve never, ever have had this issue before. It began like 2-3 days ago when the laptop would suddenly start running the fan like crazy for ~45 minutes and then would return back to normal speeds.

When the fan runs crazy, the average temperature for both the cores is ~65-70/+ C whereas normally it’s at ~30-40 C.

The RAM in the laptop fried a couple of months ago, so we had it replaced, this time installing two sticks of RAM (8 GB each). Don’t know if that has something to do with it, just adding as much info. as I can.

Specs:
16 GB RAM
i7 processor 64 bit 2.6-2.8 GHZ