HDD Failure/Won't boot without 2nd drive

[Decennium]

So I have 2 hdds right now in my rig, a WD Black 1TB(Primary) and a WD Green 1.5tb and I got this S.M.A.R.T. notice telling me my green drive needs to be replaced soon and whatnot. So.... I removed the secondary drive and now it won't boot at all. It just says Please select proper boot device and reboot, that makes absolutely no sense when the secondary drive had no ties to the boot drive.....I shove the 2nd drive back in and voila it boots again but the drive is kind of wonky as it will hang whenever I'm accessing anything from the 2nd drive. I also ran a WD diagnostic thingy and it tells me the drive is failed the reading test. How do I fix this boot problem and how do I back up something if I'm unable to read from the drive? Please and thanks.

Some specs that may or may not help with the problem
Mobo: Asus P8Z68-V PRO GEN3
CPU: Intel Core i7 2700k
Ram: Kingston HyperX 4x4gb
GPU: AMD 6950
PSU: CoolerMaster 750W

 

[Liggywuh]

Remove the 2nd Drive and enter the UEFI upon next boot (press delete during initial boot).

Then change the boot device to the WD Black drive, depending on how it is installed it might be called "Windows Boot Manager DRIVE NAME" as well.

 

[Aesma]

that makes absolutely no sense when the secondary drive had no ties to the boot drive....

Wrong. The secondary drive is actually the boot drive, since you installed windows on the other drive but left that "secondary" one plugged and it was first in the BIOS, so windows very intelligently (dumbly) installed its boot info on the wrong drive.

 

[mrkazador]

Pop in the windows disc and do a startup repair.

 

[Old Hippie]

Wrong. The secondary drive is actually the boot drive, since you installed windows on the other drive but left that "secondary" one plugged and it was first in the BIOS, so windows very intelligently (dumbly) installed its boot info on the wrong drive.

Yep.