Noise - Mobile CPU vs Desktop CPU

I've always gone with mobile CPUs in the past, but I'm considering going with a desktop CPU when Skylake comes out. My question is: are laptops with desktop CPUs significantly noisier than those with mobile CPUs?

Obviously they run hotter under full load, but do they actually hit that load as much is typical usage since they're more powerful chips? And is there a way to underclock them if, in some situations, you're more concerned about noise than performance?

Thanks!

Noise - Mobile CPU vs Desktop CPU