My all in one Hp fault, 3 long beeps followed 4 short beeps and then says adapter not supported

[Abana]

My all in one Hp Pavilion 24 fails to boot, it makes 3 long beeps followed 4 short beeps and then says adapter not supported, then turns off

[TheOldMan]

Here is a thread on the same topic

https://h30434.www3.hp.com/t5/Desktop-Boot-and-Lockup/3-long-beeps-followed-4-short-beeps-and-then-s...

Give it a read and try the solutions  - more than one to try  - and see if any of those help.

[savvy2]

NO PC told

full model

if you go to your HP support page and tell it real full model you see manuals and in those manuals are all HP blink and beep codes, for sure all POST ERRORS.

the codes change by YEARs of PC and series.

best is to look your up directly 

there are 22 favors of AIO 24 seen here none I can guess./

https://support.hp.com/us-en/products/desktops/pavilion-desktops

unplug all USB devices first?  see if boots

or see if BIOS works, power on (from dead cold off) and hammer ESC then F2

see your PCs full model there  and full product number,  both help ,  to solve why  it fails.

beeps mean serious hardware failure mostly and there are 20 steps to find it,  1 above USB is first.

if you google 3 long + 4short.

you see many telling about some alien bad,  USB wifi dongle there and is shorted  so again on all PCs made that beep

remove all USB devices first,  to see if the POST Codes like that still remain.

it is  a hard ware failure.  that we know.

PCs can FAIL pre POST , POST live or end, or OS dead.

my guess yours is PREPOST hard failed,  and is  power issue they will say

see shorted USB cable do that and even tested this my self in the lab.  Vbus+ to shields shorts are very bad, and PC now dead. (on smarter PCs, I have them too, it only shut the USB port down and boots ok but port is now dead.

self protection using smarter Vbus power reg, chips, 

that is how it works, but  all you do is unplug things to find short. up to 20 classes devices can and do short. a tech assumes this and proves otherwise. testing.  "called power fault isolation testing" in business. (for 4 decades in my case)