difference between compatibility mode and enhanced mode?

[proboscis]

I know what the difference is, one is for legacy OS's, but I saw something and don't know why it's doing it. I was booting off of a ghost CD and it wouldn't recognize my cdrom, so after changing the mode to compatibility, it worked.

But what I saw was, when it was set as enhanced mode, the HDD picked up as UDMA-2. Set to compatibility mode, it showed up as UDMA-6 (which it is). Why would that be? I even ran an HDD benchmark but didn't see any difference.

I also saw a difference in the main BIOS screen. Set to enhanced mode, I saw
primary ide master - no device
primary ide secondary - no device
third ide device - HDD
fourth ide device - CDROM

Under compatibility mode, I saw
primary ide - HDD
secondary ide - CDROM

Why would that be? I have an asus p4p800-e deluxe and an ata133 PATA hdd. thanks.

 

[DougLite]

When you enable enhanced mode, you disable ATAPI emulation on the ICH5R SATA ports. Instead, it tells the operating system that the SATA devices are on a RAID controller, requiring a F6 driver in Windows. When you use compatible mode, the SATA disks are emulated as PATA devices, and one of the PATA channels on the mobo is disabled to allow the SATA drives to take their place and be addressed as ATA drives using generic ATA drivers. This explains why Ghost detected the drives in comaptible mode, but not enhanced.

Newer versions of Ghost should support ICH5R SATA enhanced mode, are you running the latest version?

However, the weird thing here is that you describe your PATA drives being detected in enhanced mode as SATA devices - which they're not I wouldn't worry about the reported DMA mode if the drive performs the same in either mode.