Can't get AHCI to work, bios says it's still IDE, no performance difference vs IDE when AHCI "enabled" and more.

I have a ASUS Crosshair Formula IV with an Kingston SSDNow 64GB SSD.

Lets start. I started with going into my bios, then into storage configuration, i change both the 1-4 and the 5-6th ports into AHCI.

Then, i restarted, went back into bios and fixed my boot drives in the correct direction. I sat my CD drive first as i was going to install Windows 7 all over again.

I could not help to notice a few things, when changing to AHCI all of my sata tabs in storage config where gone. The second thing was that in boot options, my SSD was still stated as an IDE drive, so with my CD drive i think.

After installing Windows, i did notice a tiny boost in start up time but nothing significant. I then went on to benchmark my SSD, horrid. Write speed: around 50mb/s, read speed: around 120 mb/s. Completely abysmal for an SSD. My main computer has a Corsair Force GT and it gets way over 400 in both.

I have tried to switch on the sata cables in my computer and such too.

I then went on to check in device manager and found out that AHCI drivers where installed. I then went into regedit to check on two things, msahci and iaStorV, msahci checked out well but iaStorV was at 3 so i changed it to 0, no difference.

The last thing is, normally if you would change from IDE to AHCI and vice versa without re formatting or changing regedit, windows would bootloop, this does not happen to me, i can just change whatever i want and it works.

So, what im i doing wrong, what is wrong and why is it wrong lol....
5 answers Last reply
More about ahci work bios ide performance difference ide ahci enabled
  1. Interesting.
    Most have a boot problem trying to change from ide to ahci. The reason is that windows did not initially load the ahci drivers. In the opposite case, I think you loaded windows with ahci drivers and still had ide drivers available so you could switch back and forth.

    The ssd is sata2 which will limit the sequential speed. Also, a small ssd will not have as many nand chips that can be accessed in parallel to get maximum sequential speeds. It matters little since you are still getting the benefit of fast small random I/o which the os does mostly.

    Leave the sata mode as ahci to enable trim. It is particularly important on a small ssd that will fill up quickly.
    Past that, don't worry until the ssd approaches 80% full.
  2. The advertised speeds for your ssd are:
    Sustained Sequential Read
    100MB/sec

    Sustained Sequential Write
    80MB/sec

    So, you are not too far off from what you should be getting.

    Trim does work in IDE mode too, as long as you have win 7 or 8 on the ssd.
  3. spooky2th said:
    The advertised speeds for your ssd are:
    Sustained Sequential Read
    100MB/sec

    Sustained Sequential Write
    80MB/sec

    So, you are not too far off from what you should be getting.

    Trim does work in IDE mode too, as long as you have win 7 or 8 on the ssd.



    Really, then i guess its almost spot on. I was sure it was more because i had red somewhere that it was around 250-300 mb/s in the read section. TRIM is enabled, so i guess im in AHCI mode. I must say though, performance wise its really unimpressive, but its a couple of years old now so i guess its to be expected ;P
  4. geofelt said:
    Interesting.
    Most have a boot problem trying to change from ide to ahci. The reason is that windows did not initially load the ahci drivers. In the opposite case, I think you loaded windows with ahci drivers and still had ide drivers available so you could switch back and forth.

    The ssd is sata2 which will limit the sequential speed. Also, a small ssd will not have as many nand chips that can be accessed in parallel to get maximum sequential speeds. It matters little since you are still getting the benefit of fast small random I/o which the os does mostly.

    Leave the sata mode as ahci to enable trim. It is particularly important on a small ssd that will fill up quickly.
    Past that, don't worry until the ssd approaches 80% full.
    Well, its a bit strange. I changed to AHCI before i reinstalled my OS. It should wipe the drivers during a format, maybe it didnt? Anyways thanks for the answers guys :)
  5. I'm confised.
    The crosshair formula 4 is an AMD board and doesnt use iastor. it uses the amdsata driver for ahci unless you have your SSD connected to the jmicron controller and not the AMD controller.

    I have a feeling you are connected to the jmicron which is why enabling AHCI on the amd ports made no difference and did not cause you to error when starting windows.
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