I have solved this problem once before so feel a bit foolish I have to do it again and cannot locate my original notes.
Server: IBM X3200
old HDD: Seagate 3TB - Initialised as GPT, formatted as 3TB drive, shows up on the Server as 3TB (this from prev time solved the problem)
new HDD: WD Black 4TB - Initialised as GPT on another PC, but not yet formatted, shows up on the Server >>>in the uEFI BIOS and in DiskPart and in diskmgmt.msc<<< as 2TB
Server: IBM X3200
old HDD: Seagate 3TB - Initialised as GPT, formatted as 3TB drive, shows up on the Server as 3TB (this from prev time solved the problem)
new HDD: WD Black 4TB - Initialised as GPT on another PC, but not yet formatted, shows up on the Server >>>in the uEFI BIOS and in DiskPart and in diskmgmt.msc<<< as 2TB