Copied from a random web site:
The Quadra 700 ships with 512 KB VRAM on the motherboard. You can upgrade this to 1 MB by installing two 256 KB or two 512 KB VRAM SIMMs in a single bank. For 2 MB VRAM, install six 256 KB or six 512 KB VRAM SIMMs, filling all VRAM sockets. (Note: the Quadra 700 sees only 256 KB on a 512 KB SIMM.)
Sounds like you missed something on the upgrade. Also what monitor? You won't see extra resolution on fixed resolution monitors, only thousands and millions color option.