Nice servers! Hope you get them working - love my C240 M4 - although a bit noisier than the Dell R720 it replaced.
Be careful though - if you put non-Cisco parts (PCI-X boards, not the drives) in them they will run their fans at a much faster rate. Fortunately, genuine Cisco parts are relatively cheap on this retired hardware.
You can put them in a power efficient mode through the CIMC to keep the fan speed down a bit, which helps with the noise.
The T5820 is a superior machine, for about the same price, especially if you game as it can support higher powered graphics cards - up to a 4080 I believe.
Have a pair of them in the home office - one for me, one for the kid - they are great machines. The NVME drives in the front is a great option to get, imo - as they are blazing fast (>2Gbps).
Bought both of mine from PCSP - nice transactions on both.