The pciide driver doesn't support your Nvidia chipset. It needs extra code (specific for this chip) for DMA to work properly.
The driver was targeted towards older systems, it shouldn't be used on any board that supports AHCI. AHCI has more capabilities including NCQ and will offer better performance. You need to switch all ports to AHCI mode in the BIOS, it's unusual that some ports show up under ahci(4) and some under pciide(4). You must have two separate SATA controllers with separate config sections in the BIOS. As far as not booting from USB, you need to try booting the USB in both MBR mode and UEFI mode. I bet one will work. On some BIOS this shows up with a boot option of something like "USB STICK 3.0" for MBR mode and "UEFI: USB STICK 3.0" for UEFI mode. The "ERR M" from your previous post suggests that MBR mode isn't working and you should test UEFI mode. I don't know why halt -p doesn't work but you can try to submit a bug report using sendbug which includes all the ACPI data. I think people generally avoid Nvidia chipsets because the reputation Nvidia has for being stingy with programming details. I suspect this is more of a problem with their video chips than their motherboard chips, but the end result is the same, less people try to work on drivers for this particular brand of hardware. Chris
