What is the maximum memory capacity of my Supermicro C9Z790-CG?
The maximum memory size of the C9Z790-CG is 192GB.
The phs memory® option for my Supermicro C9Z790-CG is faster than the existing RAM - Is this a problem?
If your system is limited to a slower memory speed, the "Fallback Speed Setting" in the SPD of the phs memory® RAM-Modules ensures the support of slower memory settings down to the given memory speed.
Will the legal warranty of the device expire, if I install a new memory module?
The legal warranty right of your C9Z790-CG will not be affected if you install the memory yourself.