The R720 is the end of the line for DDR3 based systems. Simply going to a R730 gets you DDR4 and newer iDRAC is better than old iDRAC. It also lets you use V3 and V4 Xeons and it is practically the same price. My local recycler isn’t even bothering with 12gen Poweredges anymore.

You could probably throw two Dell M1000e server chassis into that as-is. Just make sure you aren’t paying the power bill.

If it is a Windows 95 server then every three days. Format and reinstall once every three months.