On Sun, 08 Jun 2014 19:24:52 -0700, Rustom Mody wrote:

> On Monday, June 9, 2014 7:14:24 AM UTC+5:30, Steven D'Aprano wrote:

>> The fact that CPUs need anything more than a passive heat sink is
>> *exactly* the problem. A car engine has to move anything up to a tonne
>> of steel around at 100kph or more, and depending on the design, they
>> can get away with air-cooling. In comparison, a CPU just moves around a
>> trickle of electric current.
> Trickle?
> Ok... only its multiplied by a billion:
> http://en.wikipedia.org/wiki/Transistor_count

A typical desktop computer uses less than 500 watts for *everything* 
except the screen. Hard drives. DVD burner. Keyboard, mouse, USB devices, 
network card, sound card, graphics card, etc. (Actually, 350W is more 

Moore's Law observes that processing power has doubled about every two 
years. Over the last decade, processing power has increased by a factor 
of 32. If *efficiency* had increased at the same rate, that 500W power 
supply in your PC would now be a 15W power supply. Your mobile phone 
would last a month between recharges, not a day. Your laptop could use a 
battery half the size and still last two weeks on a full charge.

In practice, hard drives are not likely to get more efficient, since you 
have to spin up a lump of metal. (Solid state drives tend to be either 
slow and unreliable, or blindingly fast and even more unreliable. Let me 
know how they are in another ten years.) Network cards etc. are 
relatively low-power. It's only the CPU and some of the bigger graphics 
cards that really eat electrons. Moore's Law for power efficiency is 
probably asking too much, but is it too much to ask that CPUs should 
double their efficiency every five years? I don't think so.

>> CPU technology is the triumph of brute force over finesse.
> If you are arguing that computers should not use millions/billions of
> transistors, I wont argue, since I dont know the technology.

No. I'm arguing that they shouldn't convert 90% of their energy input 
into heat.

> Only pointing out that billion is a large number in pragmatic terms - So
> is million for that matter
> - Actually not so sure even on that count
>   [Never counted beyond hundred!]

Not really. A single grain of salt contains billions of billions of 
atoms. A billion transistors is still a drop in the ocean. Wait until we 
get the equivalent of an iPhone's processing power in a speck of dust 
that can float in the air.


Steven D'Aprano

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