Prodesk 4 red beeps

[Raziane]

I purchased a 800 g1 mini second hand some time ago and recently it gave me the dreaded 4 red beep code. I checked the power supply and the inner ring was 19.53v but the pin was 18.3v so I replaced the adapter with an original hp 19.5v 3.33a ( the same as before and now the same thing) I seems to happen if I unplug it for any reason and after holding down the power button it eventually it works. I have checked for shorts, dry solder joints, loose power socket and stripped it down to bare components.

I'm going go on a limb here and say the board is on its way out

[DGroves]

HP error codes are in two parts, the first (major) beepe sequence then a pause and the (Minor) beep code follows

so if you are getting 4 beeps, a 2/3 sec pause then 4 more beeps this indicates a  video card overheating issue or possibly a power supply issue (the card's power draw may be right at the power supply's limit

are you using a addin video card or the motherboard/cpu onboard video?

if a add in card, remove and try onboard video only

https://www.manualslib.com/manual/715780/Hp-Eliteone-800-G1.html?page=199