Do higher end graphics cards require a minimum amount of main cpu speed to operate normally? And if so, why? I am planning on buying a new card with current systems specs: amd athlon 3000+ (2.16 ghz) with plenty of RAM, windows xp, 7200 rpm drive. Also it has to be an 8x AGP card. Which one would be the best? I dont really have a price range, i just want a really good card. im willing to buy another PSU as well because mine has too little power output. Thanks.

Generally, yes and no :)

more modern cards are able to do things on the GPU that older cards can't do, however most games will simply disable those effects on older cards.

Basically any SM3.0 card should be good enough for gamedev in windowsXP/Direct3D whereas a GF8 class card would be optimal for OpenGL in any OS or D3D in Vista. (not sure if there are any AGP versions of those cards yet though).

the cards that support SM3.0 are any of AMD/ATIs radeon x1xxx cards (X1300 - X1950 i think) and any nvidia GeForce card from 6200 and above. (the 8000 series can only be fully utilized using OpenGL if you run anything but Vista though)

Graphics cards may use a surprising amount of CPU. For example, the whole shader/effect system in D3D is known to be CPU hungry (binding all shader parameters for each object that needs to be rendered).

There are also various hardware things that may cost CPU, even if you don't expect it to. For example, some graphics cards may not be able to support a given feature (say, the derivative functions in pixel shaders), and instead do the calculations on the CPU and send extra streams to the vertex processing hardware (say, gradients that they can forward to the interpolators for the pixel shaders). I don't know if this particular example makes a lot of sense, but it's the kind of thing that can end up using a surprising amount of CPU for even very simple things.

A decent AGP card is the x1600pro 512mb. It should run most games on reasonable quality graphics. I have one and im happy with it. You have to understand that you are not running even a top mid-range card.

Dave

thank you for your replies. I will probably look into that x1600pro card. But I may save money for a while longer and jsut build a new system with a pci express ports.