Interesting. I'm not surprised though, because the Linux kernel will probe the hardware directly and automatically reconfigure some things to fix BIOS issues. Can you run this command to dump the PCI config registers? You just need the section for the PATA/SATA ports. Code: sudo lspci -vv -nn -xxx Then reflash to the original HP BIOS (before any DSDT mods) and re-run the same command? I'd just like to isolate if this is all the Linux kernel or in part because of our DSDT mods.