frame buffer size?

[zchieply]

i was wondering why today's gpu have such a large frame buffer ( 1 GB) when they only have to store a single frame at a time like a 1920 * 1080p which comes out to be a frame size of 5.93MB ( 1920 * 1080 * 24 bits).

 

[Lean L]

GPUs also do processing. Textures are stored on vram.

 

[MyCoder]

1 gb memory, enough for 1080p.

 

[Anarchist420]

Because of the back buffer, processing, and textures all of which are much larger than the front buffer.

 

[toyota]

1 gb memory, enough for 1080p.

why do people make comments like this? it is most certainly not enough for all games if you have a card that is fast enough to crank settings and/or use mods. plus resolution is not the only factor as some games can use lots of vram even at low res.

 

[Yuriman]

i was wondering why today's gpu have such a large frame buffer ( 1 GB) when they only have to store a single frame at a time like a 1920 * 1080p which comes out to be a frame size of 5.93MB ( 1920 * 1080 * 24 bits).

Simple - false premise. Frame buffer is not all that the ram on a video card is used for. Also, you're not storing only a single frame, either.

 

[Jaydip]

i was wondering why today's gpu have such a large frame buffer ( 1 GB) when they only have to store a single frame at a time like a 1920 * 1080p which comes out to be a frame size of 5.93MB ( 1920 * 1080 * 24 bits).

U need way more than that U forgot MSAA,pre-fetching and different subpixel level calculations.

 

[nenforcer]

Don't forget if you enable triple buffering that 3 buffers for every frame and most people want 60 frames per second.

Obviously you can discard old frames almost immediately but it still requires incredible amounts of bandwidth.

 

[guskline]

1 gb memory, enough for 1080p.

Ever run 3 monitors on 1 g Vram?

Perhaps the quote should be something along the line that :

"Except for higher reolutions or for the most modern games with all the eyecandy enabled or for multi-monitor setups, 1 G Vram is enough for 1080p"

( That sounds like a legal disclaimer!)

 

[BFG10K]

i was wondering why today's gpu have such a large frame buffer ( 1 GB) when they only have to store a single frame at a time like a 1920 * 1080p which comes out to be a frame size of 5.93MB ( 1920 * 1080 * 24 bits).

Sure, if all you ever do is show a simple 2D picture.

 

[BrightCandle]

I would be interested to see the breakdown of VRAM usage for a modern game however. I think it would be quite enlightening.

I have seen for example comparisons of reported VRAM use with the various graphical settings, the ones that often massive chunks are the higher quality textures. But still I'd like to see a detailed breakdown of something like Skyrim out of curiosity.

 

[Pottuvoi]

i was wondering why today's gpu have such a large frame buffer ( 1 GB) when they only have to store a single frame at a time like a 1920 * 1080p which comes out to be a frame size of 5.93MB ( 1920 * 1080 * 24 bits).

Usually you cannot just have 24bit frame buffer in memory the remaining 8bits are padded or have 8 alpha bits.
With HDR the framebuffer depth is usually 64bits (16bit for each component.)
Zbuffer is either 24 or 32bits and if it's 24bits there is 8bits of stencil as well.
If you use MSAA/SSAA you multiply the size of all these buffers by amount of samples 2x, 4x, 8x.

Then you have all vertexes/objects you need to use in the scene and all the textures.

Then you have all special buffers for shadow mapping etc, which can be several 2048x2048x32 buffers.. and so on.

If games uses Deferred rendering you must store all information you need for G-Buffer. (color/albedo, specular, normal, etc.)

If theres GPU side physics and special effects all must reside in there as well.

So yes, there is a proper reasons for more memory.

 

[Ben90]

Don't forget if you enable triple buffering that 3 buffers for every frame and most people want 60 frames per second.

Obviously you can discard old frames almost immediately but it still requires incredible amounts of bandwidth.

After 1, the amount of bandwidth it takes to swap buffers is virtually zero. Instead of moving the actual data of 2 to 1 and 3 to 2, it just switches the addresses of 2 to 1 and 3 to 2.