As mentioned earlier, one of the more regrettable aspects of these new CPUs and motherboards is that they require a completely new socket. Instead of LGA775 as used by Core 2 or LGA 1366 used by Core i7 900, Core i7 800 and Core i5 700 will use LGA 1156. As you'd imagine, the number refers to the number of contacts on the CPU, and pins on the motherboard. Contrary to what you might expect this doesn't mean LGA1156 is any bigger than LGA 775, indeed it's exactly the same, though LGA 1366 is markedly larger.
Along with the new socket is a new type of retention mechanism. Like LGA775 and LGA 1366, it consists of a metal plate that folds over the CPU and a sprung arm that holds it in position. However, instead of having hinges on opposite sides of the chip, LGA 1156 has the arm and plate hinges on the same side. This means that one fluid motion unlocks the arm and opens the plate. It's definitely an improvement, though of course is of little real significance unless, like us, you're swapping CPUs every other day.
Perhaps even more annoying than the change in socket is the change in cooler mount, so you'll have to factor in an extra £20 or so for a compatible cooler when you buy one of these systems. Some cooler manufacturers may be supplying replacement brackets that conform to the new fitting but they'll be few and far between.
Retail chips will be shipping with a very similar cooler to previous Intel chips - complete with the rubbish plastic retention clips - but it has a lower profile. We tested this cooler out, indeed we started out benchmarking with it, but very quickly realised that it was holding back performance. As Lynnfield is temperature-aware, it was throttling performance because the cooler struggled to blast away enough heat. We continued our testing with a Thermalright MUX-120 (provided by Intel, so it's obviously well aware its coolers aren't up to snuff) and had no further problems, so we suggest you also skip the retail version of this chip, get the OEM one without a cooler, and go for a decent aftermarket cooler.