I'm pretty sure quad core LGA 2011 will be faster than the 2600K. Otherwise it would be kinda pointless to try and sell them.
Both are going to be the going to be the same architecture, as both are Sandy Bridge. I don't think Sandy Bridge E is anything "new", rather just a designation to indicate it's the higher end platform model. If that's so, then here's what we know.
The Core i7 2600K is a four core, eight thread, 3.4GHz stock, 3.8GHz Turbo, 8MB L2 cache Sandy Bridge.
According to this, the quad core base LGA 2011 model will only be marginally better. The Core i7 3820 (notice no K) is a four core, eight thread, 3.6GHz stock, 3.8GHz turbo, 10MB L2 cache Sandy Bridge.
So.... it's pretty much the same thing, but has 200Mhz more stock speed, 2MB L2 cache, and is not fully unlocked. Whether this means overclocking is limited like the current non-K CPUs, or like the old Nehalem, is unknown, but I can say this. It's not looking to be any better (I say it's worse if it can't overclock), yet you're going to have to pay more for the platform and quad channel RAM.
So, I ask again. Why are you LGA 1366 users even looking at LGA 2011 if you say LGA 1155 isn't worth it? Unless you're planning on dropping like $700 (or whatever amount) on the six core model, the four core model is not really better (maybe worse?) than what LGA 1155 has now, plus costs more.
On top of that, Ivy Bridge is looking to hit LGA 1155 Q1 2012, but not LGA 2011 until three quarters later (Q4 2012), so if you get the LGA 2011 quad core model, you'll be behind again real fast once LGA 1155 gets Ivy Bridge a mere few months later (and rumors are Ivy Bridge may bring six core models to LGA 1155, and maybe 8 core models to LGA 2011?).
Can someone explain why LGA 2011, at least anything but the top/expensive models, is even worth it unless you are getting the six core CPU or above? The four core model is a joke, unless it has some secret advantage we don't know of yet. It's looking to be no more worth it if LGA 1155 isn't now.
Just my honest speculation. I could be wrong/overlooking something.
Edited by Princess Garnet - 7/18/11 at 10:02pm