>Thermal paste is optional, if the CPU and heatsink make good contact it doesn't make so much difference.
Err... it makes a massive difference. Try running your brand new Xeon workstation without TIM. Your PC will shut down or blow up within seconds of doing anything. Try living in Australia, or I guess Texas and doing CAD/rendering work or playing games in summer. If you don't have aircon you'll need aftermarket cooling or your CPU will throttle.
Intel used cheap thermal paste to stick the CPU to its heatspreader on their latest chip offerings instead of soldering it on. This is between CPU and heatspreader, not between heatspreader and heatsink. That alone caused load temperatures shot up by more than 10 degrees Celcius (18F). In addition to that I've reduced some of my friends' load temps by 30 degrees just by reapplying thermal paste properly and reseating the HSF.
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).
Err... it makes a massive difference. Try running your brand new Xeon workstation without TIM. Your PC will shut down or blow up within seconds of doing anything. Try living in Australia, or I guess Texas and doing CAD/rendering work or playing games in summer. If you don't have aircon you'll need aftermarket cooling or your CPU will throttle.
Intel used cheap thermal paste to stick the CPU to its heatspreader on their latest chip offerings instead of soldering it on. This is between CPU and heatspreader, not between heatspreader and heatsink. That alone caused load temperatures shot up by more than 10 degrees Celcius (18F). In addition to that I've reduced some of my friends' load temps by 30 degrees just by reapplying thermal paste properly and reseating the HSF.