I read this in a review on the SP2 at Rethinking Microsoft's tablet: Surface Pro 2 succeeds | Microsoft - CNET News
"•I understand the design better now: The fact that the Surface Pro is relatively thick for a tablet put me off at first. But I understand the necessity now. Microsoft bypassed both the Intel Atom and Core Y series processors. Those two chips, particularly the former, are power-frugal designs that would allow a thinner chassis. Instead, Microsoft opted for the mainstream U series Core i5 processor. That powerful chip requires a (small) fan and a relatively big battery to keep it going. But it's fast. Very fast."
An actual turning, motor driven cooling fan??
"•I understand the design better now: The fact that the Surface Pro is relatively thick for a tablet put me off at first. But I understand the necessity now. Microsoft bypassed both the Intel Atom and Core Y series processors. Those two chips, particularly the former, are power-frugal designs that would allow a thinner chassis. Instead, Microsoft opted for the mainstream U series Core i5 processor. That powerful chip requires a (small) fan and a relatively big battery to keep it going. But it's fast. Very fast."
An actual turning, motor driven cooling fan??