With the current market split between AGP and PCI-E interfaces, it's certainly hard for companies like nVidia to really put the hard push on just one standard. While supporting PCI-E only will give a lot of future validation support to their credit, the AGP market is much stronger, and this would alienate a lot of AMD Athlon 64 users as well as Athlon XP users who are mostly limited to AGP.
And supporting AGP only simply won't do either. This would remove you from the new Pentium 4 market as well as the Athlon 64 PCI-E segment and with AGP set for death, the results would be devastating. Both ATI and nVidia have their own ways of going about this, and with nVidia's move to native PCI-E and bridged AGP, we can say that this is more of the option we would like to see.
Native PCI-Express support allows for a cheaper overall package. With prices on DDR-2, PCI-E boards and CPU's for these new technologies up there, the cards need to be at a reasonable level for affordability. With AGP set for death, bridging the PCI-E card to run AGP is a much better idea, at it allows for compatibility, good performance and more incentive for users to go PCI-E.
The 6600GT AGP is nVidia's first PCI-E to AGP solution, and in all honesty, when looking at keeping the price at the PCI-E cards price range, a small clock performance hit is a small price to pay to have the latest technology in your AGP system. With no memory bus cuts, no cannibalising of the GPU die or any major modifications other than memory speeds, it is definitely something that nVidia has to be given credit for.
To gain that PCI-E power, overclocking is an option, as the components are identical, and easy to clock to the PCI-E level. If you want a mid-range AGP card you can't go past the nVidia GeForce 6600GT AGP since you have no mid-range level (X600 and X700) options from ATI because they are concentrating more on PCI-E which is probably fair enough considering the state of AGP at the moment.
The last question - will ATI respond with an X700 AGP bridge chip version?
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