!
error HP

Error Code Red LED blinks 10 times every second followed by a 2 seconds pause

Bad option card or expansion board.

? What Causes This

Faulty peripheral expansion cards connected to the motherboard.

How to Fix It

  1. Remove any recently added expansion slots/cards.
  2. Reconfigure BIOS setup if necessary and attempt booting again.

Source: page 2 of the official manual

From the manual

Manual page 2 — HP error Red LED blinks 10 times every second followed by a 2 seconds pause

This error code appears in:

HP Compaq Elite 8300 Small Form Factor PC