to Revert you would need to uninstall 2014.2 completely, then logon to creative cloud
and somewhere in there they give you options to install an older version.
Thats where 2014.1 should be found.
CUDA makes a HUGE difference on the Quadro 4000 cards.
I had to remove one from another workstation for a possible rma and I noticed
some projects needed rendering where they didn’t before with the quadro and cuda enabled.
Rendering in the timeline and exported content that is resized goes much quicker
as well with CUDA enabled.