Lenovo has submitted the two most recent TPC-E OLTP benchmark results, both using SQL Server 2017 running on Windows Server 2016 Standard Edition, using 28-core Intel Xeon Platinum 8180 processors.

The most recent result was for a four-socket Lenovo ThinkSystem SR950 with 3TB of RAM using a 48TB initial database size. This system had an official result of 11,357.28, which is the highest score ever submitted for a four-socket server. This system has a total of 112 physical cores, so if you divide the total score of 11,357.28 by 112, you get a measure of the single-threaded performance of the Intel Xeon Platinum 8180 processor under a full load (where the clock speed of the individual cores will be pretty close to the 2.5GHz base clock speed). In this case, the result is 101.40 score/core.

Back on June 27, 2017, Lenovo submitted a result for a two-socket Lenovo ThinkSystem SR650 with 1.5TB of RAM using a 28.5TB initial database size. This system had an official result of 6,598.36, which is the highest score ever submitted for a two-socket server. This system has a total of 56 physical cores, so if you divide the total score of 6,598.36 by 56, you get a score/core of 117.83, which is significantly higher than the result for the Lenovo ThinkSystem SR950 configured to use four-sockets (using the exact same Intel Xeon Platinum 8180 processor).

I would attribute most of this difference to the added NUMA overhead from a four-socket system, compared to a two-socket system. Another difference, which probably hurt the score of the two-socket system was the fact that it had to be running on a pre-release version of SQL Server 2017, based on the submission date of the benchmark.

This is just another piece of evidence that even with NUMA, capacity does not scale in a linear fashion as you add sockets to a server. Assuming you can split your workload across multiple database servers rather than just one, having two, two-socket servers instead of one, four-socket server will give you both more CPU capacity and better single-threaded CPU performance even when using the exact same model processor.

I would also argue that you could purposely pick a lower core count, but higher base clock speed processor from the same Intel Xeon Scalable Processor Family to find a sweet spot for SQL Server 2017 usage, where you have fewer physical cores to license, with better single-threaded performance across a higher number of servers.