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Cannot install Windows 7 on Dell Optiplex 755 using RAID 1 with 2TB drives

TechAK asked
I have a Dell Optiplex 755 that was originally shipped with WinXP Pro and setup using RAID 1 (Mirrored).  I purchased a pair of 2TB hard drives, set them up as RAID 1, and proceeded to install Windows 7 Pro.  The installed almost finishes but then gives the following error "Windows Setup could not configure Windows to run on this computer's hardware".

If I don't use RAID and install the OS on a single drive, the install finishes and the system boots correctly.

I have tried using the following RAID settings "RAID Autodetect / AHCI", "RAID Autodetect / ATA" and "RAID ON".  I get the same result on all settings.

I even tried installing an image of a working single drive OS and could not get it to boot. (Problem could have been due to the imaging software not installing a bootable image correctly, not sure as I have never used "EaseUS Disk Copy" before)

I did find a statement on the Internet where someone said that the AHCI driver has problems with drives over 2TB, I guess he ment 2TB and above?  I am not sure, is this true?

Does anybody know if you can use 2TB set as RAID 1 on this machine, and if not, can I use smaller drivers with Windows 7 Pro such as 1 TB.
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Top Expert 2010

Just use the native windows software RAID.  No driver issues, and Win7 software RAID1 performs admirably. (It even does read load balancing, so you will get much better throughput in RAID1 then you would in a non-RAID).
IT Product Manager
Top Expert 2009
Actually if you are able to install it onto single 2TB drive then the controller supports its size. Issues seemingly in generic driver for your onboard controller. Check if you are able to get an onboard raid driver and provide it during installation.
Top Expert 2012
You probably need RAID drivers, which are particular to the motherboard (not part of the OS install).  You can't install the OS unless it can find the drives, and it can't find the drives without the driver.  I would go the software route, as dlethe recommeded.


I was able to download the most current AHCI driver from Intel and provide it during the install of the OS.  Everything worked perfectly.