Well...That's a a simple question which might or might not be worth discussing...But I just wanna confirm if what I have learned so far can be applied to the real concept of graphic card. I am just wondering if the graphic card has more ram, the more pixels and color or depth of color it will display right or does it have to depend on how fast the GPU is when you choose a video card or graphic card? Don't talk about any other factors that affect it...Just focus on the graphic card for now.
think of GFX memory like cache that refreshes every nanosecond and you'll be okay. remember that everything on a GFX card works together. its the GPU that tells you how many colors you can use what your bit depth can be. however the amount of memory that is allocated can relieve bottle necks at higher Color/Bit Depth setting. the memory bus is more important than the amount of ram. instance, i have a highend 4870 with a bit bus of 256 and 512MB of memory. the midrange card the 4770 has a 1GB of memory but only 128 bit bus. in real world performance the 4870 4770 are almost neck and neck. the 4870 will always win in max setting simply because the 256-bit bus can deliver those awesome explosions 2 times faster than the 4770.
If you buy a card that is available in a 512MB version, it will probably be outdated before you need more than 512MB anyway. I only say "probably" because sometimes a game company will require something new that they don't even use, like when they released that splinter cell game that needed pixel shaders 2...and then they didn't use any of the new PS2 features. BTW...don't buy a 4870, the 5770 is just as fast, cheaper, and it has DX11 support. The 4870 was a great card, but it is obsolite and overpriced.