I'm not sure there would be much benefit to that though. It might technically have a bit more L3 cache (16 vs 20MB), but it has less L2 (3 vs 2MB), and the extra cores are not really going to be beneficial seeing as the 1600 will still perform better at heavily multithreaded tasks, in addition to being notably faster at lightly-threaded ones. For "some light gaming, virtualization, CAD, and just general use" I think they might be better served with a more modern processor with better performance per-core.
I guess the cost of used hardware could be a benefit, but then again, it's older hardware that will have no warranty. And despite being pre-owned, you would only be saving around $25 on the slower processor, and not that much on the motherboard compared to a number of B450 models. I guess the cheap server RAM might potentially make some difference if one had need for 32GB, but otherwise 16GB of DDR4-3200 can be had for under $70 new. And of course, the newer hardware will have a better upgrade path available.
That Xeon build would likely be better than an Opteron one, but when it's possible to get a faster, modern processor with 6-cores and 12-threads for as little as $85 that will outperform it in pretty much every way, it kind of brings into question how worthwhile any of those options would be.