A couple of times already, I installed Win7 on my C:-drive, but it creates a system partition on my second SSD, the one where P3D is installed. Now I had a look at the drives when installing Windows and the C:-drive was recognized as 'primary' and my P3D-drive as 'system'.

I couldnt find how to change this, so to make sure the C:-drive was used as system disc, I disconnected the P3D-drive and installed to C:

This worked and my C:-drive is now recognized as system disc, but upon checking the P3D-drive after reconnecting it, that one is also recognized as system disc.

What can I do to change my P3D-drive to primary, or whatever is relevant?

If you are willing to reinstall everything from scratch, use Diskpart to clean all your drives,

 

then uplug all drives except your OS drive and install Win7 from scratch.

http://www.sevenforums.com/tutorials/91339-ssd-hdd-optimize-windows-reinstallation.html

 

After you get Win7 installed plug your other drives back in.

 

Make sure that you shut the PC off everytime you unplug and plug drives back in.

 

How to use your Win7 install CD to get into Diskpart.

http://www.sevenforums.com/tutorials/119713-diskpart-pc-startup.html?ltr=D

Thanks, idahosurge. I just got P3D installed, so not much lots at this point. I'll have a look at it.

I had this happen when I did my initial build in 2011.

 

The user above is correct, you've gotta unplug all drives except the one you install the OS to.

 

If you don't, and the instal places that system partition on your flightsim drive, and you format the flightsim drive (at some point), you'd lose your OS functioning. This happened to me.

If you still have issue's or it happens again go to my computer, right click and select manage. Then select disk management and right click on the drive or partition in question and select change drive path. You can now change drive letters and partition size AFTER installing windows.

Thanks guys!