recurring Apple BLUE-SCREEN-OF-DEATH on iMac 27", culprit: CUDA driver? AMD failure?

Hi, my iMac 27" from 2011 is constantly crashing, blue-screen-of-death style. Unlike Windows' blue screen crash report, OS X simply halts and the display freezes in this ominous glitchy blue screen. Nothing works except unplugging power. Once booted, it goes into a crashing loop at the gray apple loading screen. sometimes it automatically reboots 5 to 10 times until it finally holds and loads OS X. I hastily moved all my files to an external HDD fearing the worst.

Here's a recount of events, if it's too long, read my conclusions below:

I acquired the iMac in 2011, bought and installed Lion in 2012. Never updated again. Never had issues of any kind. Years passed. Fast forward to September 1st, 2015: I'm editing a video in Adobe Premiere CS5. Clips are heavy and Premiere struggles. I become impatient, look for solutions, find about the Mercury Playback Engine acceleration and install the CUDA driver. half hour later, the iMac is throwing blue screens of death at me every 10 minutes.

I learn they were Kernel Panics. I imagine CUDA was causing a conflict. I Proceed to uninstall it. iMac keeps crashing. Read some more, found out AMD cards weren't compatible with CUDA (in spite of an Adobe admin assuring that so long as one had a powerful CPU, CUDA could be "enjoyed"). Turns out this thing was designed by Nvidia, for Nvidia powered systems. I cuss and remove every trace of Nvidia files from the system. No luck. I inspect kernel extension with Pacifist, further delete Nvidia entries. still screwed. I get desperate and update the system from Lion to Yosemite hoping for the issue to go away magically. It did not. I panic so I format the HFS partition and do a clean DVD install of the factory OS X from 2011. OMG WHY IS THIS HAPPENING! Snow Leopard works fine for a few hours but then the crashing begins over again!

I switch to Boot Camp's Windows 7 partition I hadn't used since 2012. The crashing stopped. I updated to Windows 10 thinking I'd stay there until I could get work done. Things are going fine until today, the Apple B.S.O.D. is back. So is the reboot loop-crashing. I didn't need to run the Apple diagnostics tool because Windows kindly reported that the AMD card had crashed. At first, Windows instantly recovered. It dodged the bullet 3 or 4 times without fatally freezing but then the Apple blue screens came back with a vengeance.

My conclusions are as follows:

1. — At no point during 4 years of constant use did the iMac crash a single time with Lion and Adobe CS5.
2. — Crashing began as soon as the CUDA driver was installed. removing it didn't help. VRAM resets didn't either.
3. — Blue-screen-of-death were recurrent on Leopard, Lion, Yosemite and Windows 10, OS failure can be ruled out, I think.
4. — the AMD card worked perfectly until CUDA. CUDA must have damaged something in the iMac.

I'm afraid of taking the iMac to an Apple Store and being told that "you need to replace your GPU card". It worked flawlessly for years until I downloaded this catastrophe called CUDA. What can I do at this point?