Can't Install Windows 8! Ensure that the disk's controller is enabled in the computer's BIOS menu!

I had this exact same issue, and JUST fixed it today. In order to do this you will need a USB drive AND an install disk.

1. Used disk utility to create a new partition, not boot camp. Boot camp creating the partition was part of the problem. I formatted the partition to ExFAT.

2. Created and ISO of windows 8 on a USB. For some reason the ISO works and the cd/DVD does not... Womp womp.

3. Restarted the computer, held down options, and then clicked the USB windows image.

4. I did still need to press format on the partition I created, but this time it worked. It installed!

5. Realized windows 8 is very upsetting and wished all games worked on mac.

I think that Boot Camp is not supporting Windows 8. Try installing Windows 7 instead. Does it works or do the same thing?

Wait, it is telling you this message on the Boot Camp setup or Windows setup?

It only works if you install on the first disk in the system. Probably your SSD. If you want to install on the opther drive you need to disconnect the SSD. Then the installation works.

But when you re-add the SSD Windows doesnt boot anymore. At least that happened for me.

So that's because it's an other drive?

As I mentioned in your other thread, Apple does not release any portable computer with 2 mass storage devices in it. With that said, their Boot Camp utility will boot only from the primary device. When you replaced the optical drive with a second mass storage device, that is an unsupported configuration and Boot Camp does not support that.

Someone else suggested that you disconnect your primary storage device to install Boot Camp on the drive in the optical bay, but as they indicated, when you reconnect the primary stoirage device, your optical bay device is now no longer the first drive in your system, so the Windows configuration will not boot properly. If you feel you must run Windows in this unsupported configuration, try using a different EFI Boot Loader instead of Boot Camp. You may have better luck, but I won't make any guarantees. You may also be able to ask for Help in a Microsoft support forum about how to get your Windows to boot again if you add a new storage drive making your current installation now on a secondary drive and no longer on the primary drive.

There are obviously plenty of examples in this forum where people use bootcamp in multi-disk environments. To say that bootcamp only supports Windows on the first HDD is kind of a stretch. You have any evidece to back that up?

By this logic, one could swap the disks in drivebay and optical bay to make the bootcamp disk the "primary one" and it should work. OSX boots just fine from the optical bay.

There are RULES when using more than one drive.

If there is a second drive it cannot be GPT.

So put where you want Windows on SATA "zero" port.

Unplug any others.

Reconnect later.

If you are going to move the SSD to optical, you probably lose your SATA3 interface which you don't want and better to put a slow non-SSD there.

This 'rule' was stumbled upon and learned back with Vista in 2006-7 on Mac Pro machines that have up to 4 internal hard drives. There are rules for UEFI and GPT.

People with iMac and SSD plus a 2nd hard drive have to go through all this as well.

Format non-Windows to FAT and MBR for instance (after making a suitable backup clone) or disconnecting the drive.

Shame it is in some user FAQs but the question should be resolved and known and in the support articles as well what to do and why.

CampTune X works well yet Apple still does not acknowledge it or other useful 3rd party tools for assisting in installing Windows on Mac. On some Macs you can use a drive dedicated to Windows only and dispense with partitioning and using BCA and just use Windows 8 DVD to do the whole install and only aferwards download + unpack and run the support software package drivers you need.

If you move Windows from A to B after install, expect to have to boot from the DVD or to see an error as it will be looking for Windows on port 0 and it will be on port 1 for instance.

That generally is the approach and direction I would take.