Again they're servers, not racks.
I'd go recycle them, they're not worth the power it takes to run them.
Well these weren't something I was going to be using but I never had a chance to mess around with DELL servers before. I wasn't serious about using them or leaving them on, it would drive me nuts from the noise and my room temperature would be over 100'F with just one without cooling plus even having one server on uses two power supplies each.
Now the rack that supports the 4 2U server has some other things in it like a KVM switch.
If anything, I'll mess around with one of them, maybe turn two of the motherboards into wall art and maybe hook up the 7 fans to a solar panel to just run. I do have people wanting to buy the rack and the rails for another project, would actually make my money back from that alone.
I guess I should mention that I was one of those people when going around neighborhoods used to see people throw out computers I would garbage pick it and just check it out and mess with the computers I would find. These days with laws, you don't see that anymore and the recycling centers I think checks computers turned it or trade them to companies that recycles them. So, I take advantage whenever I come across them.