video card shopping question number 1 - ATI/AMD(?) line vs Nvidia

[Kuciwalker]

By that you mean the memory that's also used by all other processes, right? Whereas a dedicated video card uses its own memory?

Exactly. Using memory on the chip is good because 1) it doesn't take away from normal memory the computer could use* and 2) it's much, much faster.

* graphics card memory is, however, part of the 4GB addressable space on a 32-bit machine, so it will still limit the maximum amount of system memory you can have. So with a 512MB graphics card you can only have 3.5GB of regular RAM (if you have more it will be ignored). Actually, you'll have less, because other devices also take up part of the address space.

[Asher]

Originally posted by Colon™


By that you mean the memory that's also used by all other processes, right? Whereas a dedicated video card uses its own memory? I was just talking to a friend who complained that his video card (or the drivers) eats too much memory and I was thinking of the 6200 (he wasn't sure which one he has).

Modern video cards can use the system RAM as well if necessary (not to mention stuff like the AGP Aperture and whatnot).

The difference is integrated graphics and ultra-low end add-in graphics use system RAM -- eg, the same memory used by all other processes. This is terrible for many reasons:
1) The latency is high, it needs to physically go quite a distance and over several protocols to get to the RAM
2) The bandwidth is very, very low (your average system RAM's bandwidth is 2-6 GB/s and must be shared with the CPU and was intended for the CPU, modern dedicated graphics RAM range from 16 - 180 GB/s only for the graphics card)
3) It uses your system RAM up so you can't use it

[Colon™]

Ok.

[lord of the mark]

Originally posted by Kuciwalker

By that you mean the memory that's also used by all other processes, right? Whereas a dedicated video card uses its own memory?

Exactly. Using memory on the chip is good because 1) it doesn't take away from normal memory the computer could use* and 2) it's much, much faster.

* graphics card memory is, however, part of the 4GB addressable space on a 32-bit machine, so it will still limit the maximum amount of system memory you can have. So with a 512MB graphics card you can only have 3.5GB of regular RAM (if you have more it will be ignored). Actually, you'll have less, because other devices also take up part of the address space.

fortunately my machine will only accommodate 2 gig of RAM so that shouldn't be an issue