New CPU installed but monitors not turning on.

[Threepwood]

could be wrong

no, you are correct, I posted too early, and was busy editing that in before you replied

 

[coupe69]

it's not really a stability issue btw, a lot of boards need a more recent bios to make the 508003d compatible, this is the real problem that the OP has had, if you google his motherboard you will see that it only supports the 58003d with the bios, version 12 or newer, he should have done this in advance of installing the 58003d cpu!
the only tricky thing is the bios fils on the usb needs to be renamed MSI.ROM.

The problem is the OP is having this issue with his old CPU installed. Powers on then powers off after 15 seconds. This is why he needs to get back to basics, no point trying a BIOS update when the system keeps turning itself off!

 

[freddie64]

Could installing the 5800X3d before updating have altered any bios settings so the old CPU will not work?

Using Flash Back should put a new bios on the board and get it back to basics, it's what i would do.

Presuming the OP has tried CMOS reset.