Recently I purchased a Xeon E5-2609 v4 Broadwell-EP processor as a $300 Xeon with eight physical cores but clocked at just 1.7GHz and without any Turbo Boost while the TDP is 85 Watts. Here are some benchmarks compared to other LGA-2011 v3 CPUs in my possession under Linux along with an AMD FX reference point too and followed by some Skylake Xeon benchmarks.
The Xeon E5-2609 v4 has eight physical cores (no HT), 1.7GHz base frequency (no Turbo), 20MB of Smart Cache, DDR4-1600/1866MHz support with ECC UDIMM compatible, 40 PCI-E 3.0 lanes, no integrated graphics, and is an 85 Watt TDP. I've been testing this Broadwell-EP CPU, which retails for about $300 USD, in conjunction with a MSI X99A WORKSTATION motherboard. MSI kindly sent over the new X99A WORKSTATION and it's been going great in my Linux/BSD tests. I'll have my review of it next week on Phoronix.
The LGA-2011 v3 CPUs tested for this benchmarking comparison included the others I had available: Xeon E5-2587W v3 Haswell (10 cores + HT, 3.1GHz base, 3.5GHz turbo, 25MB cache, 160 Watt TDP), Core i7 5960X Haswell-E (8 cores + HT, 3.0GHz base, 3.5GHz turbo, 20MB cache, 140 Watt TDP), and the E5-2609 v4 itself. These Haswell CPUs are higher-end, but is all I had available for LGA-2011 v3. All of the CPUs were tested on the same MSI X99A WORKSTATION + 16GB DDR4 RAM + OCZ TRION 150 120GB SSD + NVIDIA GeForce GTX TITAN X configuration. Ubuntu 16.04 LTS was used during all tests with the Linux 4.8 Git kernel and GCC 5.4.0 compiler.
For an additional reference point I also ran the CPU tests with an AMD FX-8370 system too. The FX-8370 for those that don't remember is a Vishera part with eight cores at 4.0GHz with a 4.3GHz turbo, 8MB L3 cache, and 125 Watt TDP. The FX-8370 currently retails for around $190.
As some additional tests, I also compared the E5-2609 v4 performance to some Xeon Skylakes as well: E3-1220 v5, E3-1230 v4, E3-1235L v5, E3-1240 v5, E3-1240L v4, E3-1245 v5, E3-1260L, E3-1270 v5, and E3-1280 v5.
With the CPU tests done on the MSI X99A WORKSTATION motherboard, additional performance-per-Watt metrics were carried out via the Phoronix Test Suite in conjunction with a WattsUp power meter.