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Default Enabling TRIM support in Windows 7 - 01-09-2010, 03:15 PM

If you are lucky enough to have an SSD that includes TRIM support, you may think that it is sufficient to be running Windows 7 to get the benefit of TRIM. Not so. It is required that the BIOS be running the controller in AHCI mode to get TRIM.

Before you do so, make sure that Windows has enabled the AHCI driver - this is explained in Microsoft Knowledge Base article KB922976 - otherwise you'll get an error when you reboot. To see if you already have AHCI enabled, click on the Start orb, right click Computer and select Manage. Under Computer Management, select System Tools > Device Manager. Expand "IDE ATA/ATAPI controllers" and look to see if there is an entry "Standard AHCI 1.0 Serial ATA Controller". If not, follow the steps in the KB article to enable AHCI in Windows, then boot into your BIOS and change the setting for the IDE controller to be AHCI.

Of course, there's a catch. Notebook/netbook BIOSes may not allow you to change the controller mode. The Mini 9 does not, for example, and does not run the controller in AHCI mode. I don't know about other models.

Here's how you can tell if an SSD supports TRIM.

Download and install the Intel SSD Toolbox.
Run the Intel SSD Toolbox. If your drive is not an Intel SSD, the only option available will be "View Drive Information". Click that.
Scroll down to Word 169 and look at the value for Bit 0 - Data Set Management Supported. if this is 1, you have TRIM. If 0, you don't.

(It took me most of a morning to track down which specific word and bit had this info - the ATA spec has shifted it around several times during the proposal phase.)


Steve
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