I've had this happen recently on several installs of Win7. In one case, what it really wanted was the mobos USB 3 drivers (this one was by far the most frustrating and baffling, and yes, also in this case, installing to 2 SSDs in RAID 0). Another, Intel RST drivers. Have also had cases with RAID configs where I needed to use third party software to set up partition info / format for Win7 to see it correctly for the install and not ask for drivers.
Hope that helps.