Onboard SATA versus dedicated?

[squiffy]

Would there by any difference in performance with a seperate SATA controller, such as the Adaptec AAR-1420SA? I heard many onboard SATA controllers actually run in software, it's not a dedicated controller chip. A bit like PIO mode IDE versus SCSI, the SCSI controllers had a RISC processor so CPU overhead with SCSI was considerbly lower.

Also a few years ago you could buy cache IDE controllers, I remember using one and it was blazing fast. Is anything like this available? I know drive and windows itself caches but I wonder if the there's a difference (I guess a large HD cache will be)

 

[Corasik]

If your talking 'RAID' then yes, the onboard Sata are using the CPU to help processes the raid containers. But they are fully capable SATA controllers outside the raid environment.

If the controller is part of the motherboards chipset, as with the intel ICH6/7 etc, then it has the advantage of bypassing any PCI bottlenecks.

You can get full hardware raid controllers, but you would really need one that runs on a PCI express interface, many are PCIX which is fine if you have 64bit slots, but if you just plug them into 32bit PCI slots they will be bottlenecked by the PCI interface anyway.