Question motherboard and cpu

[mrmetallica]

im trying to build a gaming pc for my grandson. ive built computers for years since days of 51/2" floppys
any way i had a motherboard given to me so bought a ryzen 7 5000 cpu but had never tried them together son when he wanted one i said hecould have them
when i put them together i got no signal couldnt work it out so bought another board but got the same thing so got a lower cpu and still the same thing im at a loss to what it is.
could the first board have been blown by the cpu not suiting the board also could the second board be blown by the cpu also he lower cpu still isnt working heeeeeelp

 

[artk2219]

im trying to build a gaming pc for my grandson. ive built computers for years since days of 51/2" floppys
any way i had a motherboard given to me so bought a ryzen 7 5000 cpu but had never tried them together son when he wanted one i said hecould have them
when i put them together i got no signal couldnt work it out so bought another board but got the same thing so got a lower cpu and still the same thing im at a loss to what it is.
could the first board have been blown by the cpu not suiting the board also could the second board be blown by the cpu also he lower cpu still isnt working heeeeeelp

Can you give us the exact models on the motherboards, and the exact cpu that you are using?

 

[mrmetallica]

the first board is a gigabyte a320m-s2h. the second a msi b450 gaming pus . the third adrus b550 elite v2
the first cpu is a ryzen 7 5000 series the second was a ryzen 7 3700