What to "update" to Xserve 2,1

[trialer2018]

Dug it up and wanted to upgrade it. Main use will be as main "computer museum" server storing all kinds of material. Need to run latest OS supported at a good performance with max RAM. Need fast boot, able to connect to Xserve RAID. M
Current Config:
- rom: XS21.006C.B06 (EFI 1.1) and LOM 1.1.2
- cpu: stock 2x2.8Ghz Quad Xeon E5462
- mem: 32Gb 667 DDR2 FB-DIMM
- gpu: ATI Radeon X1300 (stock mezzanine)
- hdd: 500GB WDC-WD5000AAKS (for booting)
Proposed Config:
- rom:
- cpu:
- mem:
- gpu:
- hdd: