ClerklyMantis

it's almost certainly a RAM thing, I feel it would specify if it were VRAM. However if you're curious about real-time utilization for both I've found that one of the best and easiest options for most people is to add VS to Steam and launch it through there and use the relatively new in game performance monitor set to "full details". It gives you everything from VRAM and RAM usage to real-time CPU Core utilization and thermals.