weird BSOD every time

Gee, you think that might have something to do with your issue?

Since your problem seems to occur only when playing games, and they started when you changed the GPU, I'd suspect an issue with the GPU.

This was probably caused by the following module: atikmdag.sys (atikmdag+0x41273)
Bugcheck code: 0xEA (0xFFFFFA8007833B50, 0x0, 0x0, 0x0)
Error: THREAD_STUCK_IN_DEVICE_DRIVER

All of your latest dumps pointed at either your GPU or its driver.

To change your driver, do the following.

Follow every step :
Step 1: Download and install the latest ati graphic driver. DONT TURN OFF OR RESTART YOUR COMPUTER AFTER INSTALLATION

Step 2: go to C:\Windows\System32\Drivers and rename atikmdag.sys to atikmdag.sys.old.

Step 3: Go to ati directory (usually in C:\ATI) and find the file atikmdag.sy_.

Step 4: Copy the file to your Desktop directory.

Step 5: Open cmd.exe by going to Start -> type cmd in the search box and hit enter.

Step 6: Change the directory to Desktop by typing chdir Desktop.

Step 7: Then, type EXPAND.EXE atikmdag.sy_ atikmdag.sys. Or,

expand -r atikmdag.sy_ atikmdag.sys

Step 8: When the expansion is complete, copy the new atikmdag.sys from your Desktop to C:\Windows\System32\Drivers