AGP 2x, 4x, 8x - whats the difference??

[Mitzi]

I have been advised that it has no effect on performance what your video card runs at so my question is what are the different AGP speeds used for???

 

[Wolfsraider]

one thing it effects is the bandwith

1x agp provides 132 mb sec

2x agp provides 264 mb sec

4x agp provides 1 gb a sec

8x agp provides 2.1 gb sec

and are independent of most pci transactions

also 8x also does 8 functions per clock if memory serves me correctly but not sure on this last point

hope this helps

 

[Mitzi]

Thanks that does help!

So I guess my question is if the increased bandwith doesn't improve performance then whats the point on having different AGP speeds

Cheers!

 

[Nocturnal]

just wondering... when are they gonna do away with pci, or come up with a new standard?

 

[Wolfsraider]

they did lol its called scsi j/k

they won't get rid of pci anytime soon as it has its uses but in the next few years the way everything is ramping up they may indeed find it too limited but...who knows?

 

[FishTankX]

In 2 years, Arapahoe will replace come in and will the the successor to PCI. Up to 2.1GB/s of bandwidth should keep that monster running for a long time..




To Mitzi, AGP speeds generally affect your worse case geometry rate.. so it doesn't show up so much..


Point in case..

How much of your unreal tournament games are spent under 60FPS? Maybe 5%. How much does super fast AGP speeds help? A whole lot!

Thus, AGP4X/8X can make a huge difference in worst case situations.

AGP is responsible for transfering textures that dont fit on the onboard memory *aswell* as geometry data .

During intense scenes, you might have 10 guys with different textures, 4 or 5 enviornment textures, and about 100,000 polygons.

That's an awful lot of data getting shoved up the AGP bus.

AGP4X is seriously getting pushed with the latest games..

AGP8X will keep AGP alive a little while longer..

Hopefully someday Arapehoe (PCI 3.0), being a serial interface, with a point to point hub, will allow SLi videocards again as well as external harddrives (Since there are only 10 or so pins, I believe, maybe only 8, the signal integrity is much better, less cross talk. It's like serial ATA vs standard ATA. )

After arapehoe comes out.. motherboard advertisers will have to advertise external PCI 3.0 slots.. lol..

And to Mitzi.. the reason why AGP4X/8X dont show up that much in benchmarks is because worst case scenarios are so rare..

An exception being CAD, in which AGP4X can lead up to a hundred percent increase over AGP2X.

Note:AGP feeds off the FSB, so the P4.. with 3.2GB/s is allowing the AGP slot to use up to 1.06GB/s of that bandwidth..

The AthlonXP is the same way, except it only has 2.1GB/s to share..

In any case, AGP8X should help worst case scenarios alot.. even if it won't do much for the 60FPS+ times..

Note:Read the FAQ's first. AndyHui has an FAQ on this!

 

[Mitzi]

FishTankX - thanks for the indepth explaination

I think I did skimp over that FAQ a while back but didn't really take it in. I only started thinking about it yesterday when I upgraded my video card.

Cheers!