AHCI can be a real pain

Published on: Author: Mike Hall Leave a comment

Did you know that an ISA video card, e.g. the old Trident cards from the early days, can put up a display on a screen which enables you to recover from a corrupted BIOS. The only problem is the complete and utter lack of an ISA slot in today’s PCs. And you thought they were just junk? PCI VGA is detected by any system, but it will do nothing to help recover from a serious BIOS fault as ISA could do.

A Microsoft serial mouse from the same period and a 5 pin DIN standard keyboard will give you mouse and keyboard functions when no other mouse and keyboard will work. PS/2 mice and keyboards have taken up the gap left by the demise of serial and  5 pin DIN since those heady days..

So what has this got to do with AHCI? No, I haven’t ‘lost it’. Read on.

AHCI creates an environment where SATA drives can be hot swapped, useful if you have an X-Port. or if you are in the habit of removing and/or connecting SATA drives on the fly. The trouble with an all SATA setup is that the Vista, Windows 7 and Windows 8 installation DVD will not boot if all SATA drives are covered by AHCI. The DVD doesn’t boot and the F6 option to load drivers from an external source is never reached.

The accepted ‘fix’ for the above is to install the OS using the Native IDE setting in BIOS, make a small registry hack when the OS has finished installing and then restart the machine, remembering to go back into BIOS to reset AHCI.

Unfortunately the above does not always work. Sometimes, the registry hack is already in place but the AHCI drivers aren’t.. Vista, Windows 7 and 8 do not install drivers which they do not need, and if AHCI is not set, AHCI drivers are not installed. Motherboard manufacturers supply AHCI drivers for XP, Vista and Windows 7 which can be downloaded and installed at the F6 option. Windows 8 is not supported by these drivers, and the only way out from this situation is to start over..

OK.. There is a drive connection standard which is not affected by any SATA settings in BIOS. It’s been around for a long time and as long as the drive is in good condition and the bootable DVD is not corrupted, an IDE DVD drive will ALWAYS boot a DVD/CD.

With AHCI set for all SATA drive ports, an IDE DVD drive will quite happily run the entire installation, and Vista, Windows 7 and Windows 8 will install the AHCI drivers such that when rebooted, everything works. You don’t have to go into BIOS and you don’t have to make any registry hack. It is foolproof.

So, when somebody tells you that the old standards are boring and that you should move on, be they hardware or software, you can smile and say to yourself ‘Yeah, right’’..

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Please note that some BIOS configurations will let you set AHCI for some of the SATA drive ports, but have a ‘get-out clause for the others, maybe two out of five or six ports. I am not sure if using the get out clause on the SATA port to which a SATA DVD is connected will allow the drive to boot from a Windows 7 or 8 DVD. I will try it out in time, but for now, the IDE drive is a great way out of a sometimes awkward and frustrating situation and works regardless.. 

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