AHCI mode

Does Win7 still require AHCI be configured before installation? I think in XP if you switched an SATA drive to AHCI from IDE, you would need to format and start over.

Error message when you start a Windows 7 or Windows Vista-based computer after you change the SATA mode of the boot drive: "STOP 0x0000007B INACCESSABLE_BOOT_DEVICE"

Thanks Greg - that is informative. So I guess the next question is, if I'm not going to be hot-swapping, is there really any benefit to AHCI?

And another one for you while you are here - can PW move a WIn7 installation? I have a newer IDE drive to replace the aged dinosaur on my kids' computer, and it wouldn't hurt my feelngs if I didn't have to do a full reinstall, since it has 4 user accounts on it.

Well what caught my eye there is the AHCI added Power Management capabilities.

I think it is the optimal, but there is a lively debate around here about whether it is that much better than IDE.

The last half dozen efforts to change to AHCI to overcome install errors have failed here. It worked once last week.

RogerR said:

And another one for you while you are here - can PW move a WIn7 installation? I have a newer IDE drive to replace the aged dinosaur on my kids' computer, and it wouldn't hurt my feelngs if I didn't have to do a full reinstall, since it has 4 user accounts on it.

Yes, it can delete, mark active/inactive, convert logical, resize, move, copy, check file system and scan HD surface.

We use it all the time here to delete dual boot XP/Vista off first partition, resize Win7 into that space, even jump Win7 over a middle data partition or from another HD into first partition space.

Start by your posting back a screenshot of the full Disk Management map.

When I was running my OS on my WD640AAKS HD, there was no difference in performance what-so-ever betweeen IDE and AHCI. Well, maybe like 3MB/s read faster. Not really any benefit.

However, when I switched to a SSD, for some reason it made a difference.
The SSD was 15mb/s faster read and 10mb/s faster write under ICHR.

Alot also depends on your motherboard and chipset, so each system will respond differently.


IMO, your best option if your really curious about permance, is do the registry hack
(if you installed under IDE) so you theres no need to re-install.
If you install Win7 under AHCI mode, you can easliy just switch back to IDE.

Boot up under IDE mode. Gives Windows 5min to finish pre-fetching etc.
Benchmark your HD's under IDE mode and remember the score.
Do this again under AHCI mode.

You will then have your answer for your particular machine/setup which offers better performance.

If the results are the same or minimal, Id just use IDE for compatability reasons.

There's no disadvantage to AHCI. No downsides at all. NCQ has been shown to have it's advantages - but for anyone who possesses an external SATA dock or drive, the hotswap ability is a quintessential feature.

Wishmaster said:

If the results are the same or minimal, Id just use IDE for compatability reasons.

Compatibility with ..?

All my drives are SATA.