Can't turn raid on

RAID means multiple disks, i only see one.

So if you haven't been using RAID on your windows drive, you can't switch RAID "on" and expect windows to boot. Since there is no array, there is no boot device and you will get blue screen. If you want RAID, you need a second harddrive of equal size and enable RAID, then enter the RAID setup and create a RAID0 or RAID1 array, save, then reboot and insert Windows/Linux operating system cd/dvd to reinstall the operating system.

Switching to RAID means everything on your drives will get lost, you can't turn it off and on when you please.

Maybe you shouldn't run RAID, if you don't understand its concepts. You see, if you don't understand RAID you might do things leading to unrecoverable data-loss. If you want safety use a second drive as backup instead. If you want speed, go buy an SSD.

The clue being missed here is that the setting is labeled, "RAID Autodetect / ATA". I'm guessing what that means is that this allows for two options in one. First, IF there is a RAID array established already, it will be detected automatically and used. (I presume also that in this mode you could use another step to establish the RAID array with multiple disks.) The OTHER option is in the "/ ATA" part. I bet this mode means that, with no existing RAID array found, the BIOS will take control of the SATA HDD and EMULATE an ATA drive with it. Now, Windows does not have a native SATA driver built in, so it cannot handle a SATA drive by itself. That leaves two choices. One is you have to install a SATA driver for it (and there are a few variations on this). The other, very much easier option, is for the BIOS to fool Windows into thinking it is dealing with an ATA drive it already has built-in drivers for, and everyone is happy!

So you were using this Emulation mode before succesfully, and your Windows still does not have a SATA driver because it never needed it. But when you told the BIOS not to do this (by setting instead to "RAID ON" ), the BIOS went into a RAID mode for dealing with the hard drive, and did NOT emulate an ATA drive. Now windows was left with no ATA drive it recognized, and no RAID drivers to deal with the RAID array the BIOS thought it was using, and no SATA drivers either! It stopped with a big error. Sounds about right. And changing the BIOS setting back to "RAID Autodetect / ATA" fixes it!