PC Perspective did a nice clock per clock comparison including Sandy Bridge, Ivy Bridge, Haswell, Broadwell and Skylake (too bad they used DDR4-2133). Comparing the last 'Tocks':
Cinebench 11.5
- Single Thread
Skylake vs Haswell: 11% advantage
Haswell vs Sandy Bridge: 9.1% advantage
- Single Thread
Skylake vs Haswell: 11.2% advantage
Haswell vs Sandy Bridge: 12.5% advantage
TrueCrypt Average
Skylake vs Haswell: 15.6% advantage
Haswell vs Sandy Bridge: 15.8% advantage
x264 First Pass
Skylake vs Haswell: 15.9% advantage
Haswell vs Sandy Bridge: 10.6% advantage
x264 Second Pass
Skylake vs Haswell: 12.2% advantage
Haswell vs Sandy Bridge: 17.7% advantage
www.pcper.com/reviews/Processors/Intel-Core-i7-6700K-Review-Skylake-First-Enthusiasts
All around a solid Tock.
Oddly enough, it looks like an L4 equipped Broadwell might be the one to get for gamers coming from older systems, if one can be had.
A Core i5 5675C close to MSRP prices will be a great option for users heavily invested in LGA1150+DDR3. It won't clock as high but it's a hair (
1.6%) faster than Skylake-S per clock in games and 14% faster than Haswell.
Skylake-S makes sense if you are coming from Sandy Bridge (maybe Ivy Bridge) or older chips and willing to build a brand new system, preferably with fast DDR4 RAM (+3000MHz).