Well considering that skylake might just bring some more serious improvements, I'd wait. That's what I'm doing, and I have a sandy aswell. It's really hard for me to justify upgrading, even to 6-cores.
New benchmarks surfaced up! *************/wipintel-skylake-core-i7-6700k-core-i7-4790k-devils-canyon-performance-benchmarks-leaked-tested-ecs-z170-claymore-motherboard/ Seems it's really close to the 5820k and I'm really considering on upgrading to 2011 instead of 1151 PS: link is to wccftech
http://hexus.net/tech/news/cpu/84626-intel-core-i7-6700k-skylake-flagship-cpu-benchmarks-surface/ If that's the same, so far 6700K 4.2Ghz = ~ 4.5Ghz Haswell chip.
Yeah it looks around the same as Broadwell @ 3.7Ghz, ~300-600mhz (depends on scenario).. Could be DDR4 limitation too.
It's a damn shame really, Intel push out two CPU's type's codename Broadwell & Skylate in 2015 & show nothing change at all. Sandy Bridge was something else & Haswell as well for laptop's but after that Intel are refresh there CPU's & calling it by a new code name by the looks at things.
"But after that" What's after that? Just Broadwell?.. which wasn't ever designed to be a desktop CPU in the first place. It's clearly a screwed up launch on a screwed up node and yet in most games it keeps pace with a 4790K (http://www.anandtech.com/show/9320/intel-broadwell-review-i7-5775c-i5-5675c/9) with 25% less power -- I wouldn't say that's "nothing change at all". Skylake isn't even out yet and I take all these leaked benchmarks with a giant grain of salt, especially after Fury X bull****, which supposedly was beating a Titan X, 8 months ago.