iMac 27" & AMD Radeon HD 6970M Issues - Thinking OS X issues

First, I am aware of the recall program in place: iMac (27-inch): AMD Radeon 6970M Video Card Replacement Program - Apple Support

Second, let me describe my problem:

• While working in OS X the screen goes black, but the computer still operate normally. You can press keyboard commands and hear the system functions.
• If I press the power button in the back to put it in sleep mode, then press a key on the keyboard to wake it, the screen comes alive for a second or two, then blacks out again.
• When I reboot the computer, the screen is black, even when holding Option, N, etc for boot options. When booting into the Network (N) install, the screen is always black, but you can hear the instructions for installation "Press the enter key to continue in English."

This started occurring a year ago, but it was mild. I could simply restart the computer and it would work normally. This past week it has just completely gone crazy. Now when it goes black, the above symptoms occur, and I cannot get the screen to stay on; just for that split second or two.

I took the computer to MelroseMac, an Apple Certified vendor, and showed them the above recall sheet. They said they found the graphics issue, as in the black screen, but the tests they performed did not qualify it for the replacement program. Great.

Now this is where it gets interesting. I have Windows 8 on a separate partition using Boot Camp. I can turn on the computer on, hold Option, and wait a bit until I know my two partitions are available for startup (OS X and Windows 8)... of course the screen is black. I press my arrow key to the right once and hit enter to get into Windows 8. THE COMPUTER WORKS FINE IN WINDOWS! HOW AWESOME IS THAT!?

So, I backed up my computer through Windows onto an external drive, booted into a network install at work which was Mountain Lion, and the screen worked perfectly. I wiped my Yosemite partition clean and installed Mountain Lion through the network install. I then proceeded to upgrade to the latest OS X, and install my Adobe CC for work. A few days later, my screen goes black again, and I run into the same scenario as above.

So what is the deal... is Apple releasing corrupt drivers? Explain how Windows works fine, but OS X is not. I have a $2,500 computer that doesn't work after OS X updates.