I've got a computer here that is running AHCI mode, and there is no mention of that fact in Device Manager at all. It has three controllers in Device Manager (using "View -> Devices by connection" mode):
- "NVIDIA nForce Serial ATA Controller" (nvstor32.sys), with two HDDs and a DVD drive connected.
- "NVIDIA nForce RAID Controller" (nvrd32.sys), with nothing connected.
- "Standard Dual Channel PCI IDE Controller" (atapi.sys), with one PATA HDD connected.
In Properties for "NVIDIA nForce Serial ATA Controller", it shows that Native Command Queuing (an ACHI only feature) is enabled. If AHCI is enabled in the BIOS, Windows will have
to use it. That's why people who change the BIOS option after
they have installed Windows will usually get a BSOD—Windows is using its generic "IDE only" or "AHCI only" driver to communicate to a controller that is now using a different protocol. However, a manufacturer-specific (i.e. non Microsoft) driver could easily detect which mode the controller has been set (by the BIOS) to use, and automatically communicate using the correct protocol. If this is your case, you should switch back and forth between IDE and AHCI mode in the BIOS without any registry tweaks or a BSOD.