noise level of PowerEdge C2100 servers?

in my home lab, i have a server room with racks where I store my 
servers. noise is typically a concern, so I've been using 4U servers 
like the PE2900 and retrofitting quiet fans into them to bring the noise 
level down while maintaining adequate cooling (I also swap out the CPUs 
for L-series or "LV" CPUs to reduce heat). I see that C2100 servers are 
now getting cheap on the used market, and was considering using them. 
I'm wondering if anyone on this list has a C2100 and was wondering what 
the noise level is like? I know it is a 2U server, so I'm concerned that 
to maintain proper cooling it requires high speed fans (4K rpm and 
above) which are typically very noisy. Wanted to confirm what the 
typical RPM range is for the stock fans? And how much CFM is required to 
keep these servers running?

also, are there any known issues that are common with the C2100 I should 
be aware of?

thanks.