the whole "IDE channel x master/slave" thing is just a red herring - doesn't matter to anything; the only thing that matters in the BIOS is that you have "SATA port native mode" enabled - turns on interrupt sharing, which makes better use of the on-die interrupt mechanism in CPUs available since, oh, around '98, and has been supported by all windoze after MilleniumEdition (which, I believe, at least eight people actually bought!); I have tested AHCI, and really see little difference - its only major advantage in my eyes is 'hot plug' for eSATAs; RAID, of course, makes a real difference, but is costly in hardware. And, by all means, turn off anything in the BIOS that you are not actually using - why waste interrupts, and make the 'queue deeper'? I do industrials, and sometimes need an old-fasioned actual, hard-interrupt serial port, as well as have an old beater of a parallel cabled plotter that will kind of creak along on an even older AutoCAD driver, but, for the main part, I leave the hardware disabled in the BIOS - when I have a need for 'em, zap 'em on in the BIOS at boot time, and windoze (all three versions) 'wakes up', sees the hardware, and plops the drivers back in, reliably, every time...