Can't find disk partition to install windows server

I just had the same problem but I solved it by unplugging the Mini SAS connector. Apparently the Windows Setup gets confused by the RAID array in the four drive bays. Now install was able to find space on a single drive, no problem.

I just installed Windows Server 2019 succesfully after like 20 hours of trying...

What I had to to:

• Create a RAID partition under 2 TB for booting (I've a 4 TB drive) (press F5)
• Mark that partition bootable (F5 too)
• Use front USB port
• Put the B120i RAID Controller drivers on the Windows USB Drive
• Replace the CMOS Battery

I replaced the CMOS Battery after like 20 hours (inluding sleep). Then booted up the computer and before I'd opened the Remote Console the installation had begun and I could select the 500 GB OS partition I'd created.

Story behind the battery change: it took me a while but suddenly I noted that the time wasn't consistent on the computer. After a nights sleep I decided to replace the battery. Someone had written in some other post that the RAID controller needs a good battery.