Video Memory

[l008com]

I have an RX 480 with 8 GB of RAM that does a great job of hashing. I also have a GT 120 with 512 MB of RAM that would probably be absolute garbage at hashing. But it doesn't even have the chance because hashcat says the card doesn't have enough memory. So how much do you need? I was thinking of buying another low end cheap card or two to give my setup a little boost, if I get a 2 GB card, will hashcat still run on it?