New System won't boot with 2nd hard drive and SSD Connected

[immrchamp]

Hello I just build a new system with 2 HDDs and a SSD. When I turn it on it tells me that "no OS was found, unplug other drives that don't have an OS on them." So I unplug the other drives and boots up. So I plugged the other 2 back in and it gives me the same error. Please help. Thanks.

 

[bjornl]

Go in to your BIOS and select which disk you want to be your default boot device.