Let's say I'm running Photoshop with some huge PSD files on a brand new iMac 27". It has 32GB of System RAM and a GTX780m with 4GB of DDR5 RAM. Will Photoshop always use the GPU RAM first because it's faster than the system RAM? If I were to get the GTX 775m iMac 27" model with only 2GB of DDR5 of GPU RAM will there be any slowdown if Photoshop when it starts using the system RAM sooner? (And yes, 32GB helps with the i7 for virtualization and many many Photoshop files running at the same time).