There are a few more things to consider: - Do you need shared storage? If so, how fast? Read or write heavy? - Do you need performant interconnect? (for say MP

There are a few more things to consider: - Do you need shared storage? If so, how fast? Read or write heavy? - Do you need performant interconnect? (for say MPI? Used IB-cards are cheap on ebay) - Is your software limited by memory bandwidth? (If so, aybe go with more memory lanes than 2) I'd rent a few different configurations from Hetzner to benchmark before buying. If you don't need more than a few nodes and you are not limited on memory bandwidth, you could consider a single, faster, node. But the sweetspot is probably consumer-grade Ryzen. As for cloud, as long as you know you'll actually use everything you buy for a long enough time period, buying will be cheaper.