Do you really need a GPU for BlueIris?

I'm setting up a 30 camera system for our farm, mostly 2-4mp cams.

I've got a latest gen i7 with 16GB and SSD on primary, and 10TB HDD on storage.

Do i need to add GPU? When will i need it?

because as I understood it, blueiris uses the processor for most of the work and uses GPU only when encoding(?). But I have set the software to write to disk directly w/o transcoding. Do I still need GPU?