Best hardware for OpenGL volumetric rendering


what type of card is better for rendering large medical volumes under OpenGL 2.1?
Are the new Quadro FX cards better than the GTX 285-295?
From what i’ve seen the quadro cards, have lower memory bandwidth and processor cores to justify their huge difference in cost.
Does anyone know?


yea a bit, technically speaking they are pretty similar, the GTX 285 is pretty darn close to Quadro FX 5800 when it comes to the gpu.
However the GTX 285 has 1GB GDDR3 Vram and the Quadro FX 5800 has 4GB, and when it comes to volumetrics i know that it can use quite a bit more ram than otherwise.

The difference in cost does not come from raw speed (although the Quadro cards can be much faster in some OpenGL applications), but from driver support: the Quadro drivers are excellent and verified to produce correct results in specific applications. You also get better support and faster response if you encounter a driver bug.

You also need a Quadro if you plan to use stereo rendering.

The memory size is not a big plus for the fx 5800. You can buy two evga gtx 285 2gb each and get the same amount of memory.
I have not used the quadro drivers, but what do you mean they are better - verified to produce correct results?
The main bottleneck in volumetric applications is the sampling for large 3d textures. Is that so much faster to justify their difference in cost?

The memory size is not a big plus for the fx 5800. You can buy two evga gtx 285 2gb each and get the same amount of memory.

You are mistaken: running two cards in SLI does not increase available memory. Each card retains a copy of all data, so effectively SLI doubles your memory requirements (or halves available memory, depending on your point of view).

The Quadro drivers contain extra options and optimizations tailored to workstation applications. This includes better acceleration for some OpenGL code paths, support for quad buffer stereo and other things - read the product sheets for more information. The gist is that Quadros are better suited “for rendering large medical volumes” and their price reflects that.

If in doubt, you should probably contact Nvidia sales support.

Alright i get it :). Thanks. I have one more question. I have tested several cards on 32 and 64 bit windows platforms to check the maximum amount of texture memory opengl allows me to use. On a 32bit platform, opengl always allows me to load 3D textures less than the video ram size (a 512mb card gives me max 256 to 384mb of textures), while on a 64bit platform opengl allows me to use more than 3 gig of memory(obviously through swapping). Why is that?

Thank you

Just an un-educated guess, so don’t read too much into this, but it might be that you are comparing two different OSes (Vista and XP?). The first virtualizes video memory (i.e. you have “unlimited” memory, constrained only by the available swap space) while the second does not (i.e. everything must fit inside the 32bit address space and the drivers are running out of addressable memory).

In any case, if you are planning to use such amounts of video memory, a 64bit OS might be a good idea.

I am not sure of this. It could be true. I have tested on a 32bit vista and 64bit xp. I am not sure yet if its an os issue but your explanation might be an answer to this.

Yes, we are planning of loading large medical volumes (more than 1 gig each) and i was mainly wondering if in terms of speed (e.g. 3d texture lookup) a quadro fx5800 is worth the money (around 3k euros) compared to an evga gtx 285 2gb which has 6 times less cost.

Buy both, do your tests, and return the slower one :slight_smile:

Or donate the slower one to your favourite charity (e.g., the brolingstanz philanthropic fund).

Basically on a 32bit os you can only adress up to 4GB of ram
This includes the vram, so you got ram-vram= available ram.

Most applications use up all of that while running something. so there is no addressing space left for cashing.
on a 64 bit system you have 4196^2 GB of addressing space, so you could actually have some addressing space left for cashing

And i agree with Stephen A, you need a 64bit os to even install the fx5800, on top of that you probably want at least 8-16GB of normal ram.
If money is an issue, get a gtx 285 or two(SLI) as you could always get the other one if needed.