[Ti] Impending speed bumps?

Chris Olson chris.olson at astcomm.net
Wed Aug 24 20:15:23 PDT 2005

On Aug 24, 2005, at 9:28 AM, John Griffin wrote:

> I wonder if there is any chance (even a very slim one) that Apple  
> could release just one low power dual core G5 Powerbook before they  
> make the final switch to Intel (?!)

It's still a thermodynamics problem.  The 970MP is only about half  
the physical size of the Pentium M, and dissipates considerably less  
heat than the Pentium, but the problem of power density remains.  You  
have a cpu with x in^2 surface area and it dissipates 100 watts (say  
this is the Pentium).  Cut the size of this processor in half  
physically (the G5) and you reduce the surface area available for the  
heatsink to absorb heat by 4 times.  Now cut the amount of heat  
dissipated by (let's say) only half - 50 watts.  Using my example  
figures, your power density is twice with the G5 what it is with the  
physically larger Pentium.

This is the major hurdle with putting a G5 in a PowerBook.

I could see a liquid cooling system where the coolant is circulated  
using the case as a heatsink to extract heat from the coolant in lieu  
of a radiator.  Aluminum has excellent thermal conductivity and even  
though the bottom of the case would get warm, if you spread it out  
over the entire surface I think it would be livable.  Just conjecture  
- I'd have to do the math on that to quantify my theory, but off the  
top of my head I'd say it would work.

If people could live with a slightly bigger PowerBook (like maybe the  
size of the IBM ThinkPad) I think it could be done with the 970MP.

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