BTW Part of that diagram is wrong. Apple removes the IHS off the top of the CPUs.
Only on the 2009 DP systems. The SP and both SP and DP 2010 models ALL use the Integrated Heat Sink.
In theory, their claims are valid (removing the IHS can improve thermal transfer between the semiconductor and the cooler), but it's not drastic, and puts the CPU in greater danger physically (i.e. over-tighten the cooler screws, and break the actual CPU).
In the case of it being needed in a MP, it's total BS, as evidenced by the 2010 models that use IHS in the DP models as well.
As per why they did it, Apple (may have been Foxconn's initiative) was being cheap,
not Intel (if you've noticed, the retaining mechanism that's usually part of the socket is missing as well). Apple had to custom order those parts without the IHS.
In the case of Intel, it may have saved a few cents per unit on production, but they required special handling that easily could have consumed those savings (i.e. must be kept separately from the rest of the production so they weren't mistakenly sent to another vendor).
Where are you finding your data for short vs. long term spec? I'd like to be able to look that up myself as sometimes I do have to run things that go on for a very long time.
It's in one of the datasheet downloads, and usually including those available publicly (obscure, so it will take some time to find, but it's usually there IIRC).
If separate, check the Thermal/Mechanical Data Sheet first. Otherwise, it's usually found in Part II.
