Why buy an older server?
Because older servers are incomparable when it comes to maximum server performance for your money.
When compared to newer processors, older processors are slower per thread, but throw raw core count at the problem, which is ideal for server workloads which are usually highly threaded such as web servers, VM Hosts and similar.
As a means of comparison, here are the CPU scores for the dual E5-2670 v2 system (20 cores, 40 threads total), which we sell for $1149-4499 with 32-768GB RAM vs current Dell servers (4-8 cores) priced between $5000-8000 with 8-16GB of RAM.
The Dell Poweredge R240, currently listed on Dell’s website for $5,000 NZD (currently on promotion, RRP of $9,500), gives half of the overall CPU performance and only 8GB of RAM vs our HP server with E5-2670 v2s with 128GB of RAM priced at only $1,649.
https://www.dell.com/en-nz/shop/scc/sr/servers/poweredge-rack-servers
If you need raw performance without breaking the bank, you won’t find any better.