Graphics Memory Sizes Compared: How Much Is Enough?

EconolineCrush writes "Trying to decide between whether or not to get a 64MB graphics card, or spring for that 128MB version? Hit up this article, which explores the performance of ATI and NVIDIA-based cards with 64 and 128MB of memory, before swiping your credit card. Not so long ago 32MB was the top end for graphics memory on consumer video cards, but now even budget cards are available with 128MB. 128MB might seem excessive now, but a year from now 64MB cards might just be obsolete."

Comments

removable RAM?

[littlerubberfeet]

this might be offtopic, but why can't the RAM on graphics cards be modular, like the stuff we stick in computers? Is it a card manufacture conspiracy? a different type of RAM? I would be willing to buy a high end Graphics card if I could eventually stick 256, or 384 MB on the card.

Re:removable RAM?

[Milican]

By soldering the RAM directly to the board there is a better connection which allows them to run the chips faster. If you add a connector then you add a capacitive load and thus you have to slow down the memory. Thats not to say modular RAM could not be incorporated down the line, but for the latest and greatest its better and cheaper to solder the stuff right on the PCB (printed circuit board).

JOhn

Re:What are you doing with it?

[andycat]

At work the two machines I use regularly for interactive walkthroughs of large environments (10-100 million triangles) have 64MB and 128MB of texture memory, respectively. I am constantly running up against the 64MB limit and I'm fast approaching the 128MB one. Here's how it breaks down:

Frame, depth, and stencil buffer: 1024x1024x(32 bits + 32 bits + 8 bits) = 9 megabytes

9 megabytes so far. No problem. Double that when I push the resolution up to 1600x1200 for demos, but we'll ignore that for the moment. Now, the model I'm using has 19MB of surface texture, so we're up to 28MB. The system I'm running on this poor hypothetical card uses 512x512 textures to replace distant geometry. Each one takes up 768K of memory and I've generally got a working set of between 40 and 60 textures. There's another 30-45MB, so total usage is somewhere between 58 and 73MB. Add in shadow maps and we lose another 20 or 30MB. The 64MB card is now swapping to AGP memory. The 128MB card is filling fast. It's adequate for the current generation of the system I'm running, but before I can write the next couple versions I'm going to have to implement some serious resident-texture-set cache management.

Now, you can certainly argue that this is an atypical application. You would be quite correct. However, I do need that much video memory and I do use it. Yes, it's massive overkill if you want to play Quake, Unreal, whatever, but once you start looking into more exotic applications it's easy to get into situations where you can use arbitrary amounts of texture RAM. Real-time shading can get you there in a hurry, too, once you start using textures as lookup tables for expensive-to-compute functions (e.g. light fields or factorized BRDFs) or caching the framebuffer for later re-use.

So yes, 90% of the programs 90% of users will run will currently fit neatly in 64MB of video memory, but there definitely exist systems that require more than that.