If you look at overclockers.com u will see that cpu's in their database are going as high as 1.85v with good aircooling, 2v+ with water or phasechange.
Another advantage of the mobile chip thats not often noted is that its max temp is rated at 100C, not 85-95 like normal ones.
One suspects this is cauz they are hand picked chips and HAVE to endure higher than normal chips given a laptops generally inferior cooling solution.
<b>My Computer is so powerful Sauron Desires
it and mortal men covet it, My Precioussssssss!
Mr no integrity coward.</b>