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critical HP
Error Code Screen Message: Display Adapter Failure (501)
Failure of the graphics adapter/graphics display controller (GPU).
? What Causes This
Faulty or loose connection in video card or monitor setup.
✓ How to Fix It
Confirm proper seating of graphics card and check monitor connections; attempt reinstallation/replacement of GPU if necessary.
Source: page 3 of the official manual
From the manual
This error code appears in:
HP Prodesk 600 G1 Small Form Factor PC