It's because you installed windows with both drives plugged in. I don't know why it happens but that occured for me as well. You *might* just have to plug the SSD into SATA port 0 (or 1, whichever is the lowest on your mobo) and see if that works. Otherwise, unplug the HDD SATA cable and reinstall windows on the SSD. After that you can plug the HDD back in.