Will it give any real advantages over AGP 8x in an A64 / 939 / x800 or 6800 / plenty good RAM pure gaming machine?
Truth is no one knows. It might make a difference, but it's unlikely at this level, but card like the All-In-Wonder or Cinema Series may benifit from PCI-EX.
I am in a similar situation, and hav been waiting for 939 and PCI-EX for some time.
EPOC just announced that they will have a P4 based (not sure which socket 7-11/Formula 409?) which will have PCI-EX and AGP 8X slot AND it will also have DDR and DDR2 support. Hopefully (for us) some of the other board makers will decide to make a similar MOBO for the socket 939 and 754 AMD64s. My preference would be a Gigabyte, with a good integrated graphics to add to it.
So if you can't afford to build often and you think this is it for 1.5-3+ years, then wait for PCI-EX, and hopefully DDR2 as well.
If you will be rebuilding this time next year, then stick with AGP, and get the fastest rig you can with whatever features you need today.
So long term go with the PCI-EX for a NEW Build.
For Short Term or if you already have a good 'CURRENT' mobo, then stick with AGP. Over the next year it won't matter much, but by this time next year I can see there being a few bottle necks out there. Of course if you save money right now, maybe you can afford to semi-rebuild next year (choice parts), and that would offer you the best performance, as likely initial socket 939, PCI-EX and DDR2 performances may be less than optimal, and by next year the solutions will be refined and the standards will likely have been pretty much determined.
Talking about the future is always a crap-shoot though.
Just my two frames worth as usual.
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