Community Newsletter: Q&A: PC video memory confusion: Dedicated, shared, discrete, oh my!

PC video memory confusion: Dedicated, shared, discrete, oh my!

by Lee Koo (ADMIN)  - 4/25/08 11:06 AM

Question:

Hi everyone. Sorry if this sounds like dumb question. I'm in process of buying a new desktop computer. When I'm looking at the specification on many desktop PCs I often get quite confused over the video memory aspect of these desktop. Some read 128MB dedicated video memory, some read integrated graphics with up to 128MB shared memory, and some read 256MB discrete video memory. Dedicated, shared, discreet? Talk about confusion! All I know in general is the more video memory the better. But can someone please explain what the difference are between these type of video specs, and what is best suited for what type of computer usage, so I can make a decent buying decision on a desktop without any future regrets. If this helps, my main goal for this new PC is for multimedia--the casual music listening/steaming, Internet surfing, e-mailing, watch videos online or DVDs, photos editing, casual gaming--nothing hard core. I don't want to limit myself to these as my interest may expand down the line. A little help in the confusing video memory area would be most appreciated!

Submitted by: Sheldon S.

Answer voted most helpful by the CNET Community newsletter readers:

Overview - Video memory


Shared Video Memory: Using part of main memory (RAM) for the display circuit's frame buffers, which temporarily hold the rendered content being sent to the screen. Shared memory is used in PCs that have the display circuit built into the motherboard rather than housed on a separate, more costly display adapter card.


Sharing main memory with the display function reduces the amount of memory available to applications, and main memory is not as fast as the specialized video memory on stand-alone cards.

On lower end systems, the video is integrated into the motherboard. The video controller uses a certain amount of 'shared RAM' for video memory. The shared ram is taken away from main system RAM. Thus, on a 512 Mb system, if the integrated controller uses '128 Mb shared video RAM', the main system only uses 384 Mb of RAM, and this is the number you'll see when checking for the memory.

When you go out to purchase a computer, some models specify that they have a certain amount of megabytes of memory, and they may have a video card that supports a certain amount of shared memory. This means that when the video card is in use, especially in higher display modes, it will take some of the memory normally dedicated to other computing activities and use it as its own. Thus, if you buy a computer with 512 Mb of memory and 128 Mb of shared memory and you frequently use a high display settings, you may actually only have 384 Mb of physical memory available left to your computer. In some advance systems, the use of Shared video memory can be changed dynamically while the system is running, that is, at one time it may be using only 64 Mb of memory out of 128 Mb shared and dynamically change it as the demand increases or decreases. While this may be fine for some people, if you have more money, you may want to go with a computer that has video memory dedicated to the video card, saving your physical memory for other uses. A computer with 512 Mb that uses 128 Mb of shared video memory will have a gorgeous display but run poorly because Windows Vista only has 384 Mb to use (minimum recommended memory for vista is 512 Mb and 128 Mb of Video memory).

Dedicated memory means that the video card uses its own memory, and doesn't share or take up the memory from your RAM. Other than that the dedicated video card would be good for graphic intense application (CAD) and video editing, games and will also help in running windows vista ( with Aero - the new Vista user interface) smoothly.

The Advantage of a video chip with shared memory is that it is cheaper, it won't be horrible, but it won't play games (lack of RAM, and I wouldn't suggest it, this excludes flash games), and video editing won't be great (but that may not apply to ripping).

I would never buy a machine with shared video memory because 20% performance loss is not worth the small price savings realized.

As far you’re requirement goes you don’t require a high level graphics card, as you said, you’ll be doing some casual gaming I’ll suggest get a lower to mid-range video card. Make sure you buy a card that matches your expansion slot type. 256MB of dedicated memory should be enough for you. You can find cards ranging from 128MB to 2GB of memory, depending on how much you want to spend. Nvidia GeForce 8400 GS/8500 GT or ATI Radeon HD 2600 Pro are my preference for a mid-range budget. Make sure the card has a HDMI, Display Port, or a DVI output. This would also help you future proof your system.

You should see my answer to Joan’s question from last week, it may help you too.
( http://forums.cnet.com/5208-10149_102-0.html?forumID=7&threadID=288637&messageID=2736738&tag=nl.e497#2736738 )

Hope this helps. Good luck with the purchase.
http://forums.cnet.com/5208-10149_102-0.html?forumID=7&threadID=291147&messageID=2750161#2750161

Submitted by Ankit B.

Here are the other selected answers:
http://forums.cnet.com/5208-10149_102-0.html?forumID=7&threadID=291147&messageID=2754292#2754292

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