all 4 of the bugchecks were due to access violations in various drivers due to bad values. I would suspect memroy corruption by a device driver or a physical ram defect.
I would look for the RAM defect first by running memtest86 booted on its own CD. if that fails to find the Issue, I would start uninstalling the optional 3rd party drivers you have on your system or turn on verifier.exe flags on the drivers to help isolate the cause of the failure. (the system will bugcheck when first corruption occurs rather than later when the corrupted data structures are used)
first memory dump was a access violation in directx
note: overclock software installed,
mixed drivers builds for video card installed? might want to check or turn off the...