Windows 7: Change IDE to AHCI in BIOS - Much better performance

Hi all
It will mean a fresh CLEAN install of Windows I'm afraid but if you have decent SATA disks change the default setting in the BIOS from IDE to AHCI.

It really WILL improve system performance --one of my big bugbears on any discussion on performance is how the I/O subsytem (generally Disks) is forgotten - yet on most home computers the I/O subsystem is often the real cause of dreadful performance.

You'll have to do a windows CLEAN install as the system will BSOD if you just change the BIOS so you won't be able to run the installer from within Windows itself. (If you can you are very lucky).

It won't effect any Virtual machines you may have however (apart from improving disk performance).


Cheers
jimbo.

I went back and forth between AHCI being on and being off on my new box that I built in July. Honestly, with almost ever task I did and with any benchmarking tool, I didn't see any real performance gain with AHCI enabled.

Unfortuantely, with AHCI on, I do have about an 8 second delay on each boot as the storage controller initializes. And since I do boot daily, and it was costing me 8 seconds which I didn't pick back up elsewhere, I just run with AHCI disabled.

I don't use it either. Intel recommends and enables it when running with raid. Does give better performance, I don't know. I stopped using raid for a while.

I have mine set to raid.

Hi there
you have to use I/O bound tasks --otherwise it won't make a huge amount of difference unless you have RAID as well.

However with LARGE photoshop files and > 1 TB size disks the I/O throughput is significantly faster than with the IDE interface - and don't forget before SSD gets cheap enough for us mere mortals to use SATA-2 will be upon us.

The other thing with AHCI is that you don't get all sorts of problems when hotplugging etc etc.

Cheers
jimbo

Whats I/O bound tasks and is it something i have to enable or install a driver for?

btw u dont need to reinstall windows. u can enable/disable ahci in reg. reboot change bios. done.

ok i thought i edit this post and let u guys know how to do so. incase anyone cares at all.

- run regedit.
- go to HKEY_LOCAL_MACHINE/System/CurrentControlSet/Services/Msahci
- right-click Start in the Name column, and then click Modify.
- In the Value data box, type 0, and then click OK.
- exit the registry editor.

This requires a reboot. so do it. enter ur BIOS Settings and enable AHCI. On boot Windows will detect the changes made and reinstall needed drivers. Requires another reboot.

Once thats done ur done. AHCI enabled

I have been advised by Patriot to use IDE while using their SSDs. They seem to think it will "cause fewer problems" I DO think AHCI will give better performance however. I have had a lot of trouble getting an answer to this. It's a good idea to do your own benchmarks. It may vary from system to system.

What is the down side to disabling AHCI? My BIOS doesn't have a setting for it I don't think.

That is one thing I have never taken the time to fully understand. Raid, Raid 0, Raid 1. I just don't get it. Whenever I have loaded an OS I have never seen or been given a choice for any Raid selections? Hell, I could be running Raid 999 for as far as I know

RAID is a Redundant array of independent disks. There are several flavors. I would just leave your BIOS alone if you're not sure what to do and things are working okay.