Are my motherboards dead?

Hello,

I have 2 desktops from a few years ago. I stopped using them because they weren't working. Today I took them out to see what the problems were (out of curiosity & wants to learn).

The problem with both desktops is there is powering up sound and fans are running, but nothing shows up in the screen.

I searched in the forum and found this post:
https://ccm.net/computing/hardware/1535-computer-boots-to-black-screen/

I followed the top answer by DJ AKSHAY and did the first 2 things he/she listed.
I placed the RAM in different memory slot, which didn't help.
I removed the RAM and powered on the PC. I do NOT hear continuous beep sounds. So, does that mean that both motherboards are broken?

Please help. Thank you in advance.