I moved myself from a KT7A or kt 133 SDram chipset and pc133 ram to a kt400, MSI-4 ultra-BSR and 512MB of PC2700 memory and well....it's been fantastic as an upgrade but to your question, I also have a Asus A7V333R motherboard with PC2100 ram that I am making for someone and on Sisoft sandra 2002 SP1, the asus setup with a kt-333 chipset and slower ddr ram modules give faster/better benchmarks (1890mb/s)than the kt-400 with pc2700 DDR ram(1830mb/s), both cas 2.5 i think. Still you would expect the fast ram modules to win but i guess the bios in this MSI-kt4-ultra motherbaord hasn't been optimised etc or something? The KT400 setup has a 2100+ XP and the KT-333 has a 1900+
Guess if you were to sum it up, I'd guess only if u want a soon to be 8X AGP cards you could go with the KT-400 than the kt-333 chipsets, well provided you can wait you could very well opt for the nforce2!
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