Meaning of 3 long beeps and 2 short beeps old Phoenix BIOS?

Your second link is interesting because at least "5 beeps" is on the list.
Now I need to find the right switch to attempt a CMOS reset before throwing the machine away.
See you!

Generally, you just need to remove the battery for a minute and put it back...

Otherwise, there should be two pins marked CLRcmos or reset near the battery... you need to connect them with metal for about 10 seconds.

Or check the manual for a JPxx.

?,

The battery is tested with a multimeter and is okay, replaced with no change in the beeps.
There is no dust, the CPU is frequently vacuumed.
With 0, 1, or 2 other RAM sticks, it doesn't make a difference.
Without the CPU and without the disk, it's the same.
With or without a graphics card in the AGP slot, it's always the same.

I'm not certain about the number of beeps;
Audio file: https://www.cjoint.com/?DAjvJsvwURz

I'm not sure about the number of beeps; I would like to post a link to an audio file, but it gets deleted almost immediately after posting.

My response from last night was deleted too...? I don't see why..?

I was telling you that my second link gives exactly what corresponds to your PC model... So in principle, no other types of BEEPS are expected.

I was also asking what you did regarding the battery and the dusting..?

And finally, I suggested starting the PC with the minimum... That is to say, without the hard drive, without any add-in cards in your machine... including the possible graphics card (you connect your screen to the VGA output on the motherboard). Remove the memory sticks... And start the PC... The beeps should change their rhythm...?

Check the screen to see if anything displays, even if it's just a dash...???

And come back here to tell what happens.

OK, this time your audio file is in place...

There are still things that can cause the issue: the keyboard... the mouse and faults in the USB ports... the CD drive... to check. And without a graphics card

But I’m leaning more towards the motherboard or the power supply.

-- If you can use another power supply, even a weak one... You could power the motherboard with it to see if you still get the same beeps...?

If yes, it’s the motherboard
If no, it’s the power supply.

Normally, with that, you should eventually pinpoint the problem.

Yes, I had a new and packaged block on hand.
With this block (Antec 350 Basiq), the beeps take longer to appear and are louder. Aside from that, it's the same.
So I will retrieve the HDD and get rid of this old machine.
Thank you

OK, this suggests that the motherboard is faulty.

You can also look for an identical motherboard (on eBay for example) and get your PC running again... for not much money... If the CPU and RAM are OK...?

You can also upgrade by changing... the motherboard, RAM, and processor... You will need to reinstall Windows and your programs... it's a half-price solution...

Or buy another one....

If you want to recover files from your old drive, you can install it as a secondary drive in another PC and you can find and copy everything.

There you go... I think your issue will end there, and if that's the case, don't forget to mark it as resolved.