Hardware Reference
In-Depth Information
with a 32-digit binary number (2 32 =4,294,967,296). If you multiply the number of pixels
necessary for the screen resolution by the number of bits required to represent each pixel,
you have the amount of memory the adapter needs to display that resolution. Here is how
the calculation works:
1920×1080 = 2,073,600 pixels × 32 bits per pixel
= 66,355,200 bits
= 8,294,400 bytes
= 7.91MiB
As you can see, displaying 32-bit color (4,294,967,296 colors) at 1920×1080 resolution
requires just short of 8MiB of RAM on the video adapter. Because most modern video
cards have at least 512MiB or more, you can see that two-dimensional images don't re-
quire much memory.
3D video cards require more memory for a given resolution and color depth because the
video memory must be used for three buffers: the front buffer, back buffer, and Z-buffer.
The amount of video memory required for a particular operation varies according to the
settings usedforthe color depth andZ-buffer.Triple buffering allocates more memory for
3D textures than double buffering but can slow down the performance of some games.
Youcanusuallyadjustthebufferingmodeusedbyagiven3Dvideocardthroughitsprop-
erties sheet.
Begin Note
As we discuss 3D in this and following sections, we are referring to the rendering of
3D graphics on your display. 3D display technologies (which involve special glasses and
120MHz or greater refresh rates on LCD or LED backlit displays) is a different issue.
Although current chipset-integrated graphics solutions feature 3D support, the perform-
ance they offer is limited by being based on older, less powerful 3D GPUs and by the
narrow data bus they use to access memory. Because integrated graphics solutions share
videomemorywiththeprocessor,theyusethesamedatabusastheprocessor.Inasingle-
channel-based system, this restricts the data bus to 64 bits. A dual-channel system has a
128-bit data bus, but today's fastest 3D video cards feature a 512-bit or wider data bus.
The wider the data bus, the more quickly graphics data can be transferred.
For these reasons, you are likely to be disappointed (and lose a lot of games!) if you play
3D games using integrated graphics. To enjoy 3D games, opt for a mid-range to high-end
3D video card based on a current AMD or NVIDIA chipset with 1GB of RAM or more.
If you demand peak performance and your budget permits, you might also consider using
Search WWH ::




Custom Search