SATA drives: IDE or AHCI mode...?

esuhl

I've just built a new PC, and am wondering whether to set the SATA hard drive(s) to IDE or AHCI mode in the BIOS. I've spent the last hour searching the web, but have just got a lot of contradicting advice.

AHCI includes all the features of IDE, but also allows hot-swapping and NCQ. So one would think it would be the best choice... but apparently NCQ can reduce drive performance in a normal desktop environment.

However, my PC seemed to boot and open Firefox quicker when I installed XP with the drive in AHCI mode. In fact, some of the people who said that AHCI mode is slower had installed the OS on IDE-mode drives, then changed to AHCI, so I wonder if changing the setting once the OS is installed causes a reduction in performance, rather than AHCI itself...?

And Intel suggest you set the SATA mode to RAID (which uses AHCI) for maximum flexibility. I definitely won't be using RAID, but this suggests that AHCI is better than IDE mode. XP doesn't have AHCI drivers by default, but I have slipstreamed them onto a CD using nLite.

So... I'm confused! I intend to install XP, Windows 7 and Slackware-64 on to the PC. Can I ask which mode you would choose (or have chosen) and why?

AirCooledHeaven

There are some benchmarks here:
http://expertester.wordpress.com/2008/07/24/ahci-vs-ide-%E2%80%93-benchmark-advantage/

To be honest while the differences are measurable I doubt you'll see any objective improvememt in 'real world' performance. When I upgraded from PATA to SATA I could measure the improvements but it really didn't have a big impact on the performance of my applications.

I imagine that if you couldn't find a definitive answer through your searches it's unlikely one mode is streets ahead of the other.

esuhl

AHCI

Thanks - that's a really good article. I've read a bit more and it looks like AHCI *might* be a bit quicker due to NCQ.

Also, I'm not sure how reliable this review of my HDD is, but it says the drive has "dual-processors for bleeding fast Native Command Queing", so maybe my particular drive will show a greater performance difference with AHCI.

I guess there's probably not much in it...