Very noob question about video memory

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novadaemon

Gawd
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Aug 24, 2006
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I've been wondering something about video memory that I've never received and answer to so I hope I can find it here.

Back in the good ol' days of the Radeon 9600 a lot of people in forums would say that having 256mb of video memory was a waste because of its 128-bit bus and that the 128mb version was just fine.

Flash forward to today and I look at a lowly 9500gt and those models sport 512mb and 1gb on the 128-bit bus.

As far as I know, the ram on that card is going to have much higher bandwidth than your standard DDR2-800 system memory, so is it a waste or what? If so, why?

If 256mb on a 128-bit bus was a waste, why bother with 512mb or 1gb on a 128 bit bus? Why bother with 1gb on a 256-bit bus? Can the card use its own memory instead of paging the system memory?
 
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bus width and memory size have little correlation. The memory size is about how much game data the video card can store on itself before having to request more data from the system. The bus width is how much of that data can be transferred to or from the GPU at a time (but not from the main system).

There's a third feature that affects performance. memory speed. a 256-bit bus running at 1500 MHz is going to move data faster than a 512-bit bus running at 700MHz.

The reason it would be a waste on that 9500GT, is because the GPU itself can't provide the performance necessary to utilize the data-set that would fill 512MB.
 
Ok, I figured as much. A little confirmation helped. Thx. Guess it really is just all marketing hype... a waste of good silicon I suppose.
 
I was asking the same question when they came out with 256MB GF4MX's.

I had a 128MB 5900xt at the time, and it was just right for the games it can run. Then i suddenly saw a 256MB GF4MX on the shelf and i went 'WTF?!'

I guess the 512MB 9500 is in the same position?

Realistically speaking, what do you do that would need that much ram?

edit: Can't remember if it was 128 or 256MB but either way it was waaay more than an MX could possibly handle. And my card before that was the GF4 ti4200 and very well aware of what it could do which an MX isn't even supposed to come close to.
 
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Well, I suppose my main concern was if the extra memory could be used for storing anything other than texture data.

For example would it be better to game on a 256mb 8800gt with 1gb of system memory or a 1gb 8800gt (i dont even know if they ever existed) on 256mb of system memory(a ridiculous scenario) due to the fact that the video memory is way faster than the system memory.

I know video memory is NOT system memory, but I just didn't get the purpose of putting all that memory on those types of cards.
 
The only reason you see low end cards 9400/9500 or 4350/4550 with 1gb of memory has got to be pure marketing. You wouldn't believe how many people think that the only thing that makes a video card good is the amount of memory on it. It is cocmpletely useless since the cards couldn't keep up with a game that needed all that vidoe ram to begin with.
 
The high amount of RAM on low-end cards is for purposes other than gaming. I have a vague idea that for 3D modelling apps like Maya, the amount of RAM on the card is far more important than how fast the card is, but I don't know much about that market.

For today's gaming purposes, you should not buy a video card with less than 512MB for any resolution. 512MB is definitely enough for resolutions up to and including 1280x1024 and 1440x900. For 1600x1200 or 1680x1050, 512MB might be enough, but 896MB or 1GB is better, while more than 1GB is totally wasted. For 1920x1200 or 1920x1080 resolution, you definitely want 896MB or 1GB, but more than 1GB is wasted. For 2560x1600, 1GB is a minimum, and more than 1GB has some benefit, but only at high levels of AA.

Another important thing to know is that when two or more cards operate in SLI or Crossfire, each card must have the same contents in RAM. That means when you have two 512MB cards in SLI/Crossfire, it only counts as 512MB RAM total; they do not combine the two amounts of RAM into 1GB (that would require an impossible amount of bandwidth between the two banks of RAM). So, when a game is running on two 512MB cards in SLI or Crossfire, the game only sees and uses 512MB.

This applies to cards with two GPUs, including the 9800GX2, 4850X2, 4870X2, and GTX 295; for example, the 4870X2 is often advertised as a 2GB card, but it actually has only 1GB per GPU. The 4850X2 has 1GB and 2GB versions, but the 1GB version is really two 512MB, and the the 2GB version is really two 1GB.
 
guitarguy6 said:
The only reason you see low end cards 9400/9500 or 4350/4550 with 1gb of memory has got to be pure marketing. You wouldn't believe how many people think that the only thing that makes a video card good is the amount of memory on it. It is cocmpletely useless since the cards couldn't keep up with a game that needed all that vidoe ram to begin with.
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Tell me about it. When i talk about gaming cards, first thing i do is ask the model. And it usually goes something like this:

Friend: Dude, can you recommend a game?

Me: Sure. What's your system?

Friend: (proudly) A pentium and a 512MB video card and i'm using Vista.

Me: ...

Friend: ...

Me: ...

Friend: ...

Me: ...and?


I've started to learn to just ask how much the video card cost instead of the model number.

@evilsofa

On 3D modeling/rendering, you're more reliant on system ram rather than video. 4Gigs is just a starting point for something like 3D Studio Max. The only way the video card can help is on the GUI and even then it's just basic wireframe meshes and some ultra low textures. Also, the position of the vertices, skeleton and physics are still done by the CPU.

It just seems strange that low end cards would be given more ram than high end ones.
 
evilsofa said:
The high amount of RAM on low-end cards is for purposes other than gaming. I have a vague idea that for 3D modelling apps like Maya, the amount of RAM on the card is far more important than how fast the card is, but I don't know much about that market.

For today's gaming purposes, you should not buy a video card with less than 512MB for any resolution. 512MB is definitely enough for resolutions up to and including 1280x1024 and 1440x900. For 1600x1200 or 1680x1050, 512MB might be enough, but 896MB or 1GB is better, while more than 1GB is totally wasted. For 1920x1200 or 1920x1080 resolution, you definitely want 896MB or 1GB, but more than 1GB is wasted. For 2560x1600, 1GB is a minimum, and more than 1GB has some benefit, but only at high levels of AA.

Another important thing to know is that when two or more cards operate in SLI or Crossfire, each card must have the same contents in RAM. That means when you have two 512MB cards in SLI/Crossfire, it only counts as 512MB RAM total; they do not combine the two amounts of RAM into 1GB (that would require an impossible amount of bandwidth between the two banks of RAM). So, when a game is running on two 512MB cards in SLI or Crossfire, the game only sees and uses 512MB.

This applies to cards with two GPUs, including the 9800GX2, 4850X2, 4870X2, and GTX 295; for example, the 4870X2 is often advertised as a 2GB card, but it actually has only 1GB per GPU. The 4850X2 has 1GB and 2GB versions, but the 1GB version is really two 512MB, and the the 2GB version is really two 1GB.
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So where does that leave me? haha...i notice everyone on here with my card (gts250) gets the 1gig version. I didnt pay enough attention and got the 512mb version. Tho in games and everything it plays PERFECTLY..no drops in FPS, the HDTV i use it on currently is 1920x1080, but will eventually go back to a 1680x1050 20" monitor. Iv never owned a Vidcard above 512mb.
 
These days i would settle no less than 1GB of ram. Games stutter a lot with antialiasing and anisotrophic in 512 in anything higher than 1280x1024. The newer games also tend to use a lot of video memory these days. You'll regret it getting 512 after getting a ton of stuttering and glitchiness in games. Only way i see use of 512 is anything below 1280x1024. More than likely we are going to see a lot more 2GB versions next generation also. Theres already 2GB versions right now but its going to be the norm for 1GB then 2GB will be what everyone wants. Gta4 can already use over 1GB. Crysis also with the High resolution texture mod. I would just get 1GB though right now ;). 2GB is still pretty expensive unless your pushing boundaries past 1920x1080.
 
Conker said:
These days i would settle no less than 1GB of ram. Games stutter a lot with antialiasing and anisotrophic in 512 in anything higher than 1280x1024. The newer games also tend to use a lot of video memory these days. You'll regret it getting 512 after getting a ton of stuttering and glitchiness in games. Only way i see use of 512 is anything below 1280x1024. More than likely we are going to see a lot more 2GB versions next generation also. Theres already 2GB versions right now but its going to be the norm for 1GB then 2GB will be what everyone wants. Gta4 can already use over 1GB. Crysis also with the High resolution texture mod. I would just get 1GB though right now ;). 2GB is still pretty expensive unless your pushing boundaries past 1920x1080.
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Guess il see what comes out (new nvidia/ATI) and sell my gts250 to my brother and buy one of the new ones that'l be 1gig or more (and hopefully better in other ways too) But so far like i said, i havent had any issues big time with games, my 8800gt 512mb played crysis SMOOTH on medium settings but full resolution.
 
More VRAM traditionally means you have more headroom for higher resolution games if your GPU can utilize it.

It's more about the overall architecture and design of the card itself rather than the individual components; if one part of a graphics card is severely lacking (GPU, VRAM, bus, etc), then you will be bottlenecked to the least common denominator.
 
guitarguy6 said:
The only reason you see low end cards 9400/9500 or 4350/4550 with 1gb of memory has got to be pure marketing. You wouldn't believe how many people think that the only thing that makes a video card good is the amount of memory on it. It is cocmpletely useless since the cards couldn't keep up with a game that needed all that vidoe ram to begin with.
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Amen to that. I had to talk my friend out of buying a 8400gs because it had 1 gb onboard and thought it would outperform the 9600GT 512 that I talked him into getting last year some time.
 
Syntax Error said:
More VRAM traditionally means you have more headroom for higher resolution games if your GPU can utilize it.

It's more about the overall architecture and design of the card itself rather than the individual components; if one part of a graphics card is severely lacking (GPU, VRAM, bus, etc), then you will be bottlenecked to the least common denominator.
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yep;) that's why i was not interested in a 9600gt with 1gb.
 
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