I have run computers without TIM, for extended periods of time, and it is perfectly possible. In fact, most people put far, far too much TIM on which gives you far worse thermal transfer than no TIM at all!
All the TIM is meant to do is fill in the microscopic gaps between the heatsink base and the top of the CPU, so it fills in the gaps where air would otherwise be. However, with a decently smooth HS and CPU, there should be a lot of direct contact between the two surfaces, and metal <-> metal transfers heat better than metal <-> thermal goo <-> metal.
If you were able to get a 30 degree drop then they probably either had far too much TIM on, or the heatsink was not making good contact with the CPU.
However, this all said, I think I have now disproven my point that the CPU is not the most complex part of building a system (not that it being integrated into the motherboard will make heatsink selection & attachment any easier).
All the TIM is meant to do is fill in the microscopic gaps between the heatsink base and the top of the CPU, so it fills in the gaps where air would otherwise be. However, with a decently smooth HS and CPU, there should be a lot of direct contact between the two surfaces, and metal <-> metal transfers heat better than metal <-> thermal goo <-> metal.
If you were able to get a 30 degree drop then they probably either had far too much TIM on, or the heatsink was not making good contact with the CPU.
However, this all said, I think I have now disproven my point that the CPU is not the most complex part of building a system (not that it being integrated into the motherboard will make heatsink selection & attachment any easier).