[/QUOTE]Most computers are shipped with RAID turned on by default even if you have one (1) hard drive. It will not affect performance and there is no need to change to ACHI. Plus it makes it easy if you want to add another hard drive and use RAID 0 or RAID 1.[/QUOTE]
Are you quite sure about this? It sounds wrong to me.
I admit that I haven't bought a commercial PC since 1995. I've used Dell PCs at a few employers, but all of them were configured by corporate IT.
I'm moderately sure that my current system (X58 chipset, ICH10R controller) not permit a pre-RAID setup with a single disk. I haven't done Intel raid for a while; has a RAID 10 setup, but it appeared to add more annoyance than performance.