Send it back if its in warranty, 3 years on E74.
Which, is:
GPU - HSIO calibration CRC failures encountered on retrain attempt (HSIO - high speed input ouput)
... So Im told by a man who knows his spuds.
If (for any reason
) its out of warranty....
Straighten board, remove x-clamps, heatgun back of GPU / H-ANA chip.
New thermal paste, apply heatsinks and washers / bolts instead of X-Clamps.