AGP vs. PCI-e

Keep in mind that the AGP cards are going away -- which means that if you want to upgrade later, you're going to have a much easier time of it if you have the PCIe. There's no sense in making your computer obsolete/difficult to modify before you even buy it.


-j

Ok, now my big question is that AGP As we all know has a faster bus speed as it runs straight to the processor (unless the processor is currently busy in which case it runs to ram then to processor like PCI&PCI-e) but yet PCI-e dosent do this as I understand it, why?

Sir_Lancelot said:

Ok, now my big question is that AGP As we all know has a faster bus speed as it runs straight to the processor (unless the processor is currently busy in which case it runs to ram then to processor like PCI&PCI-e) but yet PCI-e dosent do this as I understand it, why?

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I don't know about the "runs straight to the processor" stuff, but here's what I do know...

1.) PCI-e delivers 4Gbps bandwidth up and down, which means 8Gbps total in full duplex. AGP 8x (3.0) offers 2.1Gbps and is for the most part, unidirectional. The full-duplex behavior of PCI-e is going to allow some really interesting (and possibly impressive) enchancements for graphics. And yes, PCI-e x16 offers more bandwidth than AGP both unidirectionally and bidirectionally.

Keep in mind the bandwidth isn't acutally so important - Manufacturers have chosen to do most of the work locally on the graphics cards rather than over the bus. Even AGP 4x isn't maxed out to its potential yet and even the fastset processors cannot push the fastest graphics cards. So we've got a way to go before the extra bandwidth is really necessary.

2.) PCI-e offers more power directly from the bus. I think it is something like 75w. AGP is about 40w.

3.) PCI-e will be scalable to 32x and perhaps even beyond. AGP is at the end of its rope because of the complexity of the bus. And making it any faster is only going to increase the expense and push a dead-end standard. PCI-e is going to be less expensive in the long run because the bus is "simple".

4.) PCI-e allows dual video cards - And the appropriate bus technology to support the speed required for such a thing. AGP does not.


I don't think PCI-e wasn't really intended to throw down AGP, but it is better in many respects. I also think most manufacturers would prefer having a single bus for most devices inside a PC. PCI-e gets us closer to that reality.

Sir_Lancelot said:

I want someone to show me numbers with references that clearly prove beyond a shadow of a doubt that PCI-Express16x Video cards beat AGP8x In Every way.

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i wanted to see the same thing, lancelot...and toms hardware came through again.

here's an amazingly comprehensive chart of AGP cards, benchmarked with 3d mark, ut2k4, hl2, doom 3, and some others as of last summer

http://graphics.tomshardware.com/graphic/20050705/index.html

VS

a similar chart of PCI express carts, benchmarked with the same programs

http://graphics.tomshardware.com/graphic/20050524/index.html


aside from the 3dmark scores, the cards are ranked based on frames per second. hope these comparisons give you what you're looking for

well, pci-e is better than agp, without a doubt, but that does not imply that agp 8x is crap, agp is still pretty good for gaming, but pci is just better, he better things dont nessesarily mean that the ones after them are crap, they are just better, like the p4 and the anthlon, yes the anthlon is better for gaming, but doesnt mean that p4 isnt, anthlon its just better.