spec sheet one-upsmanship
sappo said:
To be honest, Im not quite sure what the difference between AGP 2x,4x,8x is. But check this out. http://www.firingsquad.com... The BX chipset is agp 2x running at 89mhz (133 with a 2/3 multiplier) and the intel 815 is 4x, but the BX is clearly faster. What's more, everything is IN SPEC on the BX board except the AGP bus (89mhz). My question is, why cant today's boards overclock the AGP but leave everything else in spec? Also what is the difference between 2x/4x/8x was when refering to AGP, and why would a 89mhz/2x AGP clean up on a 66mhz/4x AGP.
You have to look beyond simplistic numbers when evaluating complex systems. BX does not clean up on i815 simply because of the speed the AGP bus runs at, there are many more factors than this. BX is just a better chipset than i815, and it possessed a similar edge over all its period rivals.
Just because 4 is bigger than 2 doesn't really mean anything. BX has superior memory performance that allows it eclipse the performance delivered by it's rivals. Looking at any one spec or rating and blaming the difference in real world performance on this is pure folly.
The truth is even just 2x AGP is plenty fast. 4x AGP brings a tiny improvement to even today's cutting edge systems. AGP 8x is unneeded, but is being pushed by the chipset manufacturerers because last years products had 4x. They just love to point to their new products and say "we have 8X!". Unfortunately the graphics card manufacturers are adding this useless capability to their cards in order to appear modern and worthwhile. In truth even dropping back to 2x AGP rates has little impact on performance.
If the chipset and/or card you desire happens to implement 8x AGP, so be it. If not don't worry about. 4x AGP, even at 66MHz, has plenty of bandwidth for current and near-future needs.
AGP was actually created by Intel as a smoke show to make K6 platforms seem behind the times. Same motivation as the introduction of 8x AGP, to make the competition look dated. When the K6 was introduced it made quick work of the P-MMX chips and rivaled the vastly more expensive P2's. AGP was created under the auspices of allowing the graphics card fast access to system ram, rather than relying on the local fram buffer on the video card. Since K6's did not run on the 440LX chipset which was the only AGP alternative for some time, it was just marketing material designed to make K6's look second rate, not employing the most up to date technology. The fact was you could run the PCI, AGP, or AGP 2X versions of any graphics card of that era and measure no meaningful performance variance.
Since ram has gotten very cheap AGP as a texturing buffer is next to obsolete. It is a simple matter to place enough memory on the video card to eliminate any substantial degree of AGP texturing. The only real world benefit of AGP is the increased bus speed over PCI, and 2x-4x AGP rates do produce better performance now, unlike when AGP was introduced many years ago. 8x simply won't be needed for some time, just like AGP 4X wasn't needed when VIA pushed this spec sheet one upmanship on the buying public in the 694 family years ago. 3 years later AGP 4x is just starting to earn its keep, and in similar fashion it will be several more years before AGP 8x is really useful.
