It seems like, since the Xeon 5600 series was released around 2011, your system is a legacy one and probably non-UEFI.
I have some experience with Clover and I can possibly help you. See my post #817 here.
Step 1 : creating a Clover USB key that works
Since, when booting on your Clover key, you do not get the Clover menu but a black screen instead, you did not succeed in creating a Clover key that works. Latest versions of Clover are well known to cause problems with legacy systems. Because of this, I suggest that you try to create a Clover key using the BD Utility and Clover v.4961 (it worked for me and several other users who had a legacy system).
You will need a Windows system. You will find instructions and the 2 files you need in an attachment to my post #833 here.
Step 2 : installing your OS
Once, and only once you have managed to create a Clover key that boots and displays the boot menu, you can install your OS on your PCIe NVMe drive.
With the Clover menu on the screen, insert your OS installation disk (USB or CD ROM). A new entry should appear in the menu. Select it and see what happens then. Does it launch the OS installation process ? If it does not, I have other suggestions for you to try.
By the way, which OS are you trying to install on your PCIe NVMe drive ?