So for some extra benchmarks today, using toggles from the MSI C236A Workstation BIOS, I ran a number of multi-threaded Linux benchmarks when a Xeon E3 1280 v5 had just one core enabled, two cores, three cores, four cores, and then four cores with Hyper Threading.
All other settings were maintained the same.
To see all of the benchmarks, visit this OpenBenchmarking.org result file for many more data points from a small fraction of the Phoronix Test Suite's open-source, multi-threaded test arsenal.
Of course, via OpenBenchmarking.org / PTS you can also normalize the results easily:
To see the normalized results, visit this OpenBenchmarking.org link.