Video card memory size

[Richard Principal]

how does one work out the memory needed in the video computer card, The results from google seem a bit vague

this seems to be how I ended up with a formula,

(Verticle * horzontal) pixel * color depth / 8
(8 because the memory is in 8 bits wide)

So for 1024*768 at 32 bit color = 786 432 * 32 = 25165824/8 = 3.145728 Meg

 

[3iMaJ]

I would think that would only suffice as a lower bound. The screen refreshes itself 60 times a second, so to just have 1 "screen picture" in the memory at any one time would make refreshing very difficult. Typically the more memory you have the sloppier you can be.

 

[HarveyH42]

Google was kind of vague because depends on the video card, your computer, and what sort of software you will use. Basically, if you mostly do text based stuff on your computer, you can get by with what comes on the card. If you do graphic intensive stuff, video games. 3d rendering/modeling, animation, movie editing... you will want as much as you can.

Some video cards share memory with your computer, so increasing your system RAM will improve your video performance.

It doesn't really matter, if your software doesn't make use of the extra memory. Might want to see what they recommend.

Doubt there is any single equation to figure this out in all cases.

 

[philba]

as was said, it's complex. Consider that most recent cards can support larger than 1024x768 and also have wider aspect ratios (other than 4:3). Todays LCD computer monitors are often 1680 x 1050. Also some graphics engines have multiple pipelines, alpha blending, shaders and so on. That's why you find 256 MB of ram on higher end cards. Also, modern operating systems can place video objects in non-visible video memory to allow faster overall performance.

However, note that some of this is about marketing. 256 MB MUST be better than 128MB.... (dripping sarcasm alert)

 

[justDIY]

anything more than 16mb is not used for storage of the actual video image.

most of the memory is used to cache textures and already rendered 3d objects for use by the GPU. Direct X and OpenGL are both graphics technologies that support the use of texture memory. So a video card with 256 or 512mb of ram will be able to cache more data then a card with 64 or 128mb of ram. When the cache runs dry or fails to 'hit', the GPU must request data from main system memory (thank goodness for DMA, so the GPU doesn't have to run the request by the CPU first)

Also the faster the GPU, the faster it can chew through its memory. So the newer the card, the faster the GPU and the more memory it will need to feed its rendering hunger.

 

[Sceadwian]

Modern PC games will generally take advantage of whatever memory you have for textures, loading more at one time and causing less blotchy lag in the game when it has to swap out unused textures for new ones. If you're playing a lot of hardcore video games a lot of memory is a good idea, but for the average user the amount of memory a video card has is irrelevent. Many cheaper systems don't even have dedicated video memory, they just share system memory. This is lackluster in the performance department but it works all the same.