Asus ROG Crosshair VIII Dark Hero X570

Hi guys!
Have a customer with the above mobo....
When it came to me there was a whole load of tests I needed to run an even though the initial error was pointing to a memory issue it turned out to be the processor... AMD Ryzen 9 5950X
If you guys had seen the state of the processor and Noctua NH-D15 you would have been horrified....
I even had memory errors which turned out to be the processor....the person that applied the thermal paste should be banned from working on computers!!
Ok to cut a long story short...the builder of the computer made a pigs ear of the thermal paste and it caused the processor to eventually fail......
I have a test processor at the moment and that is a ryzen 5 5600G....this processor has been stable for all tests and now I don't even get memory errors....
I have been able to work on the computer for several hours without it freezing once....before it was freezing about five minutes after logging into Windows...
Now my problem is this... the customer has G.Skill 4 x 16 GB = 64GB DDR4 3600MHz CL16 Trident Z Neo C
I have tried to setup the bios with the memory frequency - but after several attempts the it starts in safety mode...
I thought that this processor should allow me to set the frequency to 3600 but as said no dice...
My customer is going to replace the faulty Ryzen 9 5950X with a new one - but that will probably be a guarantee issue with the company that built the computer...
So at the moment I am stuck with this processor....am I right in thinking I should be able to set the frequency to 3600 which is what the memory is...?
Can anyone give me some pointers as to what I can test....?

bookie56