Do you actually get real RoI on that thing? Must have cost magnitudes more than normal desktop hardware. Or is this where you just accept that it's worth it purely for tingling the geek inside you?
My dad got me a really good deal ($600!) on the RAM on ebay, otherwise I think 64gb would have been plenty. The nice thing about it is the Linux buffer cache keeps everything in memory, the SSD is just for durability.
Over 4 years of heavy software development I think the system has paid for itself in time saved.
Old server hardware can be very cheap, although it's not necessarily the best value. Typically it only makes sense if 1) you need a lot of memory, 2) you don't mind a slightly higher power bill and 3) you don't care about single core performance.
I've used a 12-core Haswell Xeon as a desktop for about five years (got it used for around $500, plus $200 for a brand new LGA 2011 v3 motherboard). At the time it was twice as fast as a high-end desktop 4-core CPU. It's still reasonably competitive on multithreaded workloads versus a recent 6 core desktop CPU, but fares poorly on single-threaded tasks. DDR4 was a bit expensive back then, but quad channel memory helps in that you can buy lower density DIMMs. Today, even DDR4 ECC RDIMM server pulls are dirt cheap. I picked up 4x16GB DDR4-2400 RDIMMs for just $90 last year.
I'll probably replace it with a 5900X soon, but it's served well over the past five years. Certainly much better than a i7-4770K box from the same time.
A faster compiling machine is the difference between sustaining a state of flow critical to developer productivity, or not. Paying even $5000 for a desktop that yields probably a 2x improvement in productivity for someone paid at least $10K a month is a total no-brainer.
Compile time impact is a very non-linear thing. There's a narrow band that could be called the distraction threshold. An investment in faster hardware will give very small returns if you are already below that range and only moderate returns when so far above that the investments only gets you a little closer. But when the speedup crosses that narrow band or at least significant parts of it, it's a night and day difference.
I think 2x improvement in productivity is a pretty optimistic number unless you don't write much code and mostly just compile it. In heavier workloads there certainly can be decent ROI though.
I built a TR 3960X (24 core) 32GB of RAM workstation for $3000, including a 700 dll graphics card (2080 Super). Realistically a 100 dollar graphics card would've sufficed for my usage (development). So it could've been built for $2400.
Depending on the context such a machine could be very cheap or very expensive, but even here in Mexico that's about one month of an engineer's salary, which I don't find too outrageous for a primary tool which lasts for years.
Depending on your workload, the performance improvements could be very noticeable (running multiple VMs, compiling, and unit testing at the same time). It does open up faster workflows if you adjust to the new speed.
Over 4 years of heavy software development I think the system has paid for itself in time saved.