Updated March 31, 2016: Today, Intel has released the fourth generation, 14nm Xeon E5-2600 v4 processor family, code-named “Broadwell-EP”. This is a Tick release from Intel, taking the existing Haswell microarchitecture, and shrinking it from 22nm to 14nm. This new family of processors has more physical cores, a larger total shared L3 cache size, and support for up to DDR4-2400 memory. There will doubtless be a few other minor improvements, as part of the Tick release.

These processors are socket compatible with the current Intel Xeon E5-2600 v3 family, “Haswell-EP”, so they should just need an updated BIOS to work in existing model servers that currently support Haswell-EP. What that means for most people is that existing model servers from your server vendor of choice will be able to use these new processors as soon as they are available, meaning less delay to market.

From the official Intel ARK database, I have put together a list of what I think are the best models at each core count for SQL Server usage.

 

ModelCoresBase Clock SpeedTurbo Clock SpeedL3 Cache
Xeon E5-2637 v443.5 GHz3.7 GHz15 MB
Xeon E5-2643 v463.4 GHz3.7 GHz20 MB
Xeon E5-2667 v483.2 GHz3.6 GHz25 MB
Xeon E5-2640 v4102.4 GHz3.4 GHz25 MB
Xeon E5-2687W v4123.0 GHz3.5 GHz30 MB
Xeon E5-2690 v4142.6 GHz3.5 GHz35 MB
Xeon E5-2697A v4162.6 GHz3.6 GHz40 MB
Xeon E5-2697 v4182.3 GHz3.6 GHz45 MB
Xeon E5-2698 v4202.2 GHz3.6 GHz50 MB
Xeon E5-2699 v4222.2 GHz3.6 GHz55 MB

Table 1: Recommended Intel Xeon E5-2600 v4 Family Processors for SQL Server

Notice the dramatic drop in base clock speeds as you go with higher core count models than the eight core Xeon E5-2667 v4 model. Also notice the amount of L3 cache per core decreasing with the higher core count models. It is not clear whether the Xeon E5-2687W v4 (which is meant for workstation use) will be available for server from the major vendors or not. The previous E5-2687 v3 was available, just requiring higher wattage power supplies.

What this means is that most people are going to be much better off from a pure performance perspective with the eight core or lower core count models. They will have much better single-threaded processor performance and much lower SQL Server 2014/2016 licensing costs. The downside is less total CPU capacity, meaning less scalability, as long as you don’t run into storage or memory bottlenecks before you run into CPU bottlenecks.

If your workload can be split across multiple, two-socket database servers, you would be much better off with two or even three database servers, with lower core count, “frequency-optimized” processors (especially the Xeon E5-2643 v4 and the Xeon E5-2667 v4) rather than a single two-socket database server with a much higher core count processor model.

For example, two Dell PowerEdge R730 servers with the eight-core Xeon E5-2667 v4 would be far superior to one Dell PowerEdge R730 server with the sixteen-core Xeon E5-2683 v4 processor. You would have much faster processor cores, more total L3 cache, twice the memory capacity, and twice the number of PCIe 3.0 slots, for the same SQL Server 2014/2016 licensing cost. The cost of the extra server would be pretty negligible compared to the total cost of the hardware and SQL Server licenses. You could probably even go down to the six core Xeon E5-2643 v4 in each of the two servers, dropping your total SQL Server 2014/2016 licensing costs by over $50K.