Question on what is the faster hard drive setup

By nickc ยท 9 replies
Sep 28, 2010
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  1. In the BIOS it gives me the option to set the hard drives to AHCI or PCI and I may have stated that wrong but those of u that know computers will understand what I said. Is AHCI faster or does it matter in Windows7?

  2. captaincranky

    captaincranky TechSpot Addict Posts: 13,005   +2,532

    AHCI has the faster >> buss << speed. This is SATA 2 @ 300-Gbs/sec.

    The IDE setting is normally ATA 100 @ 100 MBs /sec (Note the different measurement standard Giga bits vs Mega bytes....)!

    In practice, there wouldn't be much discernible speed difference with mechanical HDDs.

    If ACHI is available however, you should take advantage of it. SATA running as SATA (AHCI) is hot swappable, therefore you can plug or unplug Esata drives, even internal drives, without powering down. I saw a case the other day offering a hot swap bay, specifically for the purpose of hot plugging internal HDDs right into the front of the case.

    Also, if you elect to acquire an SSD in the future, that would be able to take advantage of the faster SATA 2 interface.

    You must make up your mind though, before you do the OS install. If you install Windows and choose IDE, you would have to reinstall the OS to run AHCI.
  3. nickc

    nickc TechSpot Paladin Topic Starter Posts: 923   +11

    Actually, I am running a SSD and with Win7 the system will install the drivers.


  4. crunchie

    crunchie Malware Helper Posts: 728

    You still need to select it in bios beforehand :).
    AHCI can also be enabled after an installation, but it can be a bit of a fiddle.
    Just be aware that if you install with AHCI enabled, every time you have need to reset the bios, it will default back to IDE.
  5. nickc

    nickc TechSpot Paladin Topic Starter Posts: 923   +11

    Maybe I did not make myself understood, I had windows installed, I went into the bios activated AHCI, winodws7 installs and enables all the features and I am running without any problem.
  6. en0nym0us

    en0nym0us TS Member Posts: 65

    I had installed Windows7 recently in IDE mode. After installation, I switched to AHCI mode. After rebooting, Windows7 installed some drivers for the AHCI mode. Everything worked fine except Windows7 no longer was able to see my CD/DVD drives. I reinstalled Windows in IDE mode.

    When I was in AHCI mode, I noticed that Windows7 was able to identify my external hard drive instantly and it seemed as if the boot time was faster. When in IDE mode, in order to get Windows7 to identify my external hard drive, I have to manually go into device manager and click on 'scan for hardware changes.'
  7. nickc

    nickc TechSpot Paladin Topic Starter Posts: 923   +11

    I run an external hard drive for backup but everything works fine with it. I think every MB is different earlier I had installed Windows7 with AHCI and then later turned it off and everything worked fine, I have an older MB that I first installed Windows7 while using it and it would not even let u install any windows if AHCI was on in the BIOS.
  8. captaincranky

    captaincranky TechSpot Addict Posts: 13,005   +2,532

    I think you made a tactical error here, but I can't prove it. I still think that Windows has to be installed with the BIOS set to AHCI, and not switched afterward. I'm curious as to whether that's why you lost functionality. I have a new H-55 board that I installed Win 7 in AHCI mode from the jump, with a SATA optical, and I guess I'll find out if I'm right about this if I ever try to install any true IDE drives. Who knows though, I might get a rude awakening. The BIOS I suppose is the issue here. It would be interesting to know how well the newer ones handle mixed mode situations. I guess if I wasn't so lazy, I could just plug an IDE optical into it, and see what happens. I'm a big proponent of not wasting the IDE buss, while saving the SATA ports for HDDs, which can benefit from the connection speed, whereas optical drives can't.

    This effect is because SATA (AHCI) is hot swappable. You can even go inside the machine running, and connect or disconnect SATA devices without harm or reboot. Running ACHI, you can swap Esata drives to your heart's content, and they'll be picked up instantly.
  9. Leeky

    Leeky TS Evangelist Posts: 3,797   +117

    That'll be the reason for my hard drives all being listed in "Safely remove hardware" then!

    I did wonder why! :D
  10. captaincranky

    captaincranky TechSpot Addict Posts: 13,005   +2,532

    Help Me End This....,I Just Can't Take it any More...........!!

    I just checked my machine running SATA, and you can indeed, "safely remove hardware" on all of the attached HDDs. I noticed you can also, "safely remove" the Windows drive! One supposes that this is the equivalent of assisted computer suicide.

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