Take the Core i7, shave off one memory controller and replace the high bandwidth QPI link with Intel’s slower DMI and you’ve got the makings of a (more) mainstream Nehalem. Many have been calling this processor the Core i5 although I’m not quite ready to jump on that bandwagon, so I’ll keep referring to it by its socket (LGA-1156) or codename (Lynnfield). The new socket requires a new cooler. The four mounting holes are closer together on the LGA-1156 socket than they are on LGA-1366 boards, but further apart than LGA-775. It’s just different enough to require a brand new cooler, or at least a new mounting bracket.
Instead of crippling graphics on its mainstream platform, Intel did the next best thing and integrated 16 PCIe 2.0 lanes onto the die of its mainstream Nehalem part. All of the processors are quad-core Nehalems with the same cache sizes as the Core i7. The only crippled beast is the entry level Lynnfield that has Hyper Threading disabled. The current rumors in the press are that Lynnfield is being held back in order to clear out excess Core 2 Quad inventory before it ships, because once this thing ships no one is going to want a Penryn anymore. Based on what I've seen, Lynnfield isn't ready just yet - it's not an artificial delay. The motherboards are in rough shape, CF/SLI isn't working and we're still at very early revs of the CPU's silicon. While I think that the chip will be ready far in advance of its rumored September shipdate, the CPU and motherboards aren't yet.
http://www.anandtech.com/cpuchipsets...oc.aspx?i=3570
Intel Core i5 Review - Few Months Before Release
Intel Core i5 Review - Few Months Before Release 
