!!
critical HP
Error Code 5 blinks, 1 blink every second followed by a 2 second pause
Pre-video memory error.
? What Causes This
Faulty memory or incorrect configuration.
✓ How to Fix It
Ensure all DIMMs are properly seated and conform to the system’s requirements and specifications. If no resolution, try replacing faulty RAM module(s).
Source: page 2 of the official manual
From the manual
This error code appears in:
HP Elitedesk 800 G1 Small Form Factor PC