AHCI vs IDE

[andy3]

Do you recommend going AHCI?
I have to instal new system and I have the option to go AHCI Vs IDE on bios.

Is it good for audio works?

Thanks

[Retrofreak]

I prefer AHCI moving forward as it allows me to dual boot with OSX.

[teknatronik]

Yes, with a new install go ahci if you have sata.

[valis]

If you're using Win7 there's no reason not to use AHCI

[andy3]

yep it's W7 and HD is ncq ready.
T.Y.

[Timur Born]

Doesn't matter that much in practice. Current SSDs' throughput can be higher via AHCI, that's mostly it. If AHCI works fine on your system then use it, because it is current technology. If it does not work fine and IDE works then just use that.

[oxide54]

Originally Posted by Timur

Doesn't matter that much in practice. Current SSDs' throughput can be higher via AHCI, that's mostly it. If AHCI works fine on your system then use it, because it is current technology. If it does not work fine and IDE works then just use that.

it does matter .

AHCI is faster

[blacklion]

Is there a way to revert to IDE from AHCI safely? If so, what does this entail?

[Aof]

Originally Posted by Timur

Doesn't matter that much in practice. Current SSDs' throughput can be higher via AHCI, that's mostly it. If AHCI works fine on your system then use it, because it is current technology. If it does not work fine and IDE works then just use that.

It DOES matter. When using AHCI, features like native command queuing are enabled, which allows for better performance.
There is no reason at all for not using AHCI, so why using the older technology???

[Aof]

Originally Posted by blacklion

Is there a way to revert to IDE from AHCI safely? If so, what does this entail?

If you are using windows XP and you revert to IDE from AHCI, you will most certainly get a Blue screen of death at startup. Not sure about windows 7, but keep in mind that the controllers loaded for your OS disk are AHCI, if you revert to IDE in BIOS, when the OS tries to initiate, all kinds of conflicts arise. I really don't know if there is a way to do it safely.
But, again, perhaps in Windows 7 is different, I changed my motherboard, CPU and memory and I just plugged the Hard Disk with my old Windows 7 installation, and it was able to initalize, although it took a lot more to initialize the first time as it changed to new drivers, but windows 7 was able to cope with the changes. Doing that in XP would have never worked for sure.

[valis]

To enable ACHI on WinXP (when on IDE drivers):
HOWTO: enable AHCI mode after installing Windows - PC Perspective Forums

To do so in Win7 you can simply change the setting in your registry:
GUIDE - Enabling AHCI mode AFTER Windows 7 Installation - Guru3D.com Forums

[blacklion]

Originally Posted by valis

To enable ACHI on WinXP (when on IDE drivers):
HOWTO: enable AHCI mode after installing Windows - PC Perspective Forums

To do so in Win7 you can simply change the setting in your registry:
GUIDE - Enabling AHCI mode AFTER Windows 7 Installation - Guru3D.com Forums

I actually enabled AHCI after installing W7 following that 2nd guide I believe.

I've noticed the occasional hiccup when streaming large track counts. Ruled out DPC spikes and tried the windows vs. manufacturers' drivers but it still happens on occasion. I'm on a Quad Core 9550 so maybe it's better left at IDE?

I didn't ever have this problem on XP so I was looking for a way to go back safely and try it out. Should I just retrace my steps following that guide?

[valis]

It's probably not directly related to AHCI, though if the device shifted in your ACPI map/DSDT it's possible you landed closer to another device that's not releasing resources in time. I would look at reducing the load that other things are placing on your system, insure that HPET is enabled in the bios & etc before worrying about AHCI.

[Timur Born]

Originally Posted by Aof

It DOES matter. When using AHCI, features like native command queuing are enabled, which allows for better performance.
There is no reason at all for not using AHCI, so why using the older technology???

Somehow I really knew this would come up. So let's debunk a few more myths.

First of all: Native Command Queuing (NCQ) is only useful when the "queue deep" of your drive is regularly higher than 1, which during normal desktop operations is not so often the case (usual peaks are around 4, with averages below 1!), but audio operation may get there regularly. Because of the additional overhead it may even be detrimental to use NCQ on a mechanical HD used for simple desktop operations.

NCQ is *not* an exclusive feature of AHCI, it's part of the SATA specification and as such also present in IDE. The default Microsoft driver may or may not support it (I guess it does), but vendor specific drivers usually do. I've been using NCQ on my old Nforce4 board in IDE mode already, which was years ago from now when AHCI wasn't widespread anyway.

Furthermore, at least the standard Microsoft driver also supports TRIM with its IDE driver. I would have to do a thorough search again to find the reference for that, but again, TRIM is part of the SATA specification and as such not bound to AHCI.

So unless I missed something I do not see why AHCI would be absolutely needed for mechanical HDs and even for SSD it's not mandatory, but rather a bonus. I'm using AHCI on my bootcamped Macbook Pro (via a boot-sector hack) and as a drawback I cannot sent it to sleep anymore (while using Windows), because the MBP "BIOS" is faulty for that. I did not have to edit the Registry for Windows 7 to go back and forth between IDE and AHCI. It's all give and take.

[valis]

Timur is correct, the advantages are not so clear in the 'real world', performance differences are marginal and command sets are still largely the same. At the same time I'll restate, if you're on Win7 the disadvantages are also only that you have to do a registry edit & bios edit to make the change if you did your initial install without AHCI enabled.

I use AHCI because I have 6 devices attached, my bios only allows 4 if I'm not in AHCI mode. I also am not 100% clear on how all bios's handle Legacy IDE mode in regards to 2 drives per logical controller. (In the PATA days only a single device was accessible at a time when there was a master/slave relationship, and this assumption may be carried over to some drivers or bios implementations even if the hardware configuration isn't the same)

[oxide54]

that XP guide only works if you have an intel AHCI controller, the amd one is different.

its similar except the driver names are different so are the registry keys.

[andy3]

The important thig is that ahci doesn't make mess for audioworks

[csl]

AHCI allows for hot-plugging drives, doesn't it? I find this pretty handy when backing-up.

[valis]

Originally Posted by csl

AHCI allows for hot-plugging drives, doesn't it? I find this pretty handy when backing-up.

For e-SATA yes...

[andy3]

Originally Posted by valis

For e-SATA yes...

Strange. I haven't Ahci but my e-Sata (mobo controller) goes hot-plug.
Isn't it?

[Timur Born]

Like TRIM and NCQ hot-plugging is part of the SATA specs (v2 specs, but can be included in v1 controllers). AHCI is just a universal protocol to communicate with the controller.

[valis]

It may differ depending on your ICH; my ESB2 southbridge only allows hot plugging eSATA (when I use a rear bracket) with AHCI enabled, but I know that ESB2 is based on a significantly older ICH than the consumer boards that were shipping in 2008.