I'm a sucker for stability, I'd go with the more stable motherboard any day, even if that means paying a price premium. As for integrated stuff on the motherboard, take for example Tyan's Thunder K7, nice motherboard, lots of intergrated stuff, would do nice in a server. But for me I'd rather have the option of choosing my own parts, especially things like SCSI controllers, NICs etc. Therefore the Tiger K7 is much more appealing to me simply because it only has the bare essentials.
As for RAID and onboard sound, I think RAID is a good thing to have as it only adds a few $$$ to the price, and I might use it now or in the near future to solve some of the disk I/O bottleneck. Onboard sound is another thing, although some solutions offers a really good implementation, for example Analog Devices's SoundMax 3.0 the usual AC-97 stuff isn't good enough for me, and I always choose a Live!.
As for performance, I think a motherboard's performance is firstly dependant on the chipset used, you can't make a Ferrari out of a Volkswagen, secondly on the board layout, you can't drive 120Mph on a wiggly, wobbly road, and lastly on the BIOS, someone has to tune that Ferrari's engine to make it go fast right? Pardon the analogies, but these three factors determine, for the most part, a motherboards performance.
Considering the fact that most motherboards closely follow the guidelines given by the chipset manufacturer for their board layout you won't see huge differences in performance there, as most manufacturers will more or less adhere to those. The BIOS however can be tweaked, with more stringent timings, less wait-states, etc. however this usually means that we'll reach a point where the thin line between performance and stability is crossed and we then end up with a fast, but unstable motherboard.
As with BX motherboards at some point you stop looking at performance but rather start caring about more/better features, quality of components used, board layout. I think the same holds true for most motherboards featuring chipsets that have already had every last bit of performance extracted from them, as with the Via KT133A. New chipsets will probably bring better performance, but new motherboards based on them will quickly become non-distinquishable from one another after the BIOS has been tweaked and upgraded over time.
That's my take on the matter, but like I said, I'm all for stability, performance is second.
CEO, Hardware Analysis
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