Does AHCI give any performance benefit

[d3fiant]

I have an Abit AB9 Pro running 3 SATA drives and 1 SATA DVDRW. Ive been running in AHCI mode but the startup is 60 seconds longer than if they are in IDE mode as it detects and spins up the drives in sequence. My question, is there any real world performance increase in using AHCI. I use mostly Vista HP but use XP for gaming

[gilgamesh]

I have an Abit AB9 Pro running 3 SATA drives and 1 SATA DVDRW. Ive been running in AHCI mode but the startup is 60 seconds longer than if they are in IDE mode as it detects and spins up the drives in sequence. My question, is there any real world performance increase in using AHCI. I use mostly Vista HP but use XP for gaming

cant give you figures, but I have heard on some forums I t indeed is an advantage to run with ACHI, AS RUNNING sata disk in IDE mode is similar to a compatibility mode and therefore not ruunning the drives at the fastest speed.

gilgamesh

[Richh]

My question, is there any real world performance increase in using AHCI. I use mostly Vista HP but use XP for gaming

If anything, in your usage scenario, you are likely to see a slight performance decrease as a result of engaging AHCI mode.

The key reason for this is that the native command queueing, assuming your drives are capable of it, fractionally increases latency, which only tends to be outweighed by the benefits of queueing in a usage scenario where there genuinely are loads of concurrent read/write requests being made.

This usually means a server of some sort. Even "power" desktop and workstation users are unlikely to be pushing the queue depths fast enough.

[Richh]

cant give you figures, but I have heard on some forums I t indeed is an advantage to run with ACHI, AS RUNNING sata disk in IDE mode is similar to a compatibility mode and therefore not ruunning the drives at the fastest speed.

Not sure what you're quoting but you seem to be using the theory rather than reality here.

You are correct to suggest that IDE mode is primarily there for compatibility with legacy operating systems. However, it also has the neat side-effect of disabling command queueing on drives that support it. This, as mentioned above, can boost performance.

On at least some boards, running in IDE mode will also force an SATA generation II drive to run at the "150MB/sec" interface speed, rather than the "300MB/sec". However, this has minimal impact on performance as the difference only affects transfers direct from the hard disk's cache memory rather than from the platters themselves.

In most home/power/office user scenarios, the performance benefit of disabling NCQ tends to outweigh the demerit of the slower interface, hence IDE being the quicker of the two modes in the real world - and that's forgetting about the boot delay the AHCI BIOS causes.

[d3fiant]

appreciate the responses chaps, I spose the good side is that I can simply set it to IDE from AHCI without the need for a rebuild