3D Accelerator Video Memory Calculator

This form is designed to allow you to calculate the video memory that a game will require in different video modes, and the effect that changing video options will have on video memory requirements.

Instructions

• The default values are acceptable for most games. Clicking on the Reset button will return all values to the default.
• Color Depth is usually the same as your desktop color depth.
• Frame Buffers: Most games use double buffering. Unreal engined games use triple buffering unless manually set to double buffering.
• Most FPS games Use Mip-maps by default. Since some video drivers also support auto-mipmapping, you should leave this item checked unless you have turned them off both in the game and in your your video driver.
• Texture Depth is not necessarily the same as color depth. Check your game settings if you are unsure.
• Texture Detail refers to the texture detail (sometimes "texture quality") setting used in the game, if available. Use "High" if the game does not have a setting for texture detail.
• Texture Usage is intended to represent the number and size of textures in a typical scene.
  • Select low Texture Usage for most FPS games.
  • Select medium Texture Usage for large or highly detailed Quake II and Half-Life levels.
  • Select high Texture Usage for Quake III and Unreal engined games (due to their higher texture resolution) and large outdoor games like Tribes (due to the high number of textures).

What it Means

• The calculation adds the number of frame buffers selected, plus one auxiliary buffer (Z-Buffer or Z + Stencil Buffer) of the same depth, plus the full uncompressed size of textures. Actual memory requirements can vary widely. Features such as environment maps, bump maps, and detail textures can all raise memory requirements significantly. FSAA may require up to 16 times larger frame buffers. On the other hand Z-Buffer Compression and Texture Compression techniques may significantly reduce the amount of memory required.
• Early video cards had hard partitions between buffer memory and texture memory. If either quantity was exceeded, an error would result, consequently for older cards you should check both the buffer size and the texture size.
• Modern video cards do not normally have partitioned memory, however even modern cards must have the entire buffer space in local memory.
• Most AGP video cards can read textures directly from main memory, as can some PCI cards. The total amount of memory available to an AGP card is the sum of the card's local memory, plus the AGP aperture size.

Some Advice

• Many games allow you to run with a color depth that is different from the texture depth. Using high color depth with low texture depth will often allow you to improve the appearance of the game without a huge penalty in frame rate.
• Triple buffering may allow for smoother play, but it increases video latency. For best results in on-line play, stick to double buffering.
• With most high performance cards made since 1998, mipmaps will not improve performance. You are better off turning them off in order to conserve local video memory.
• Decreasing texture detail is one of the most powerful ways of improving performance in marginal situations. Decreasing texture detail by one notch decreases the size of the textures in memory by 75%, which then not only increases available video memory but also decreases bus usage.
• Reading textures directly from main memory results in a significant reduction in performance, therefore even with AGP cards you should always try to run games in a mode which allows the entire video memory requirement to fit in the graphics card local memory.