What the Megahertz Myth means

S

StarManta

Guest
We're all aware that a 1.0 GHz G4 is not the same as a 1.0 GHz Pentium. I found this information some of you may find useful:

Both the Athlon and Pentium 4 use longer pipelines (long and thin) with simple stages whereas the PowerPC G4s use shorter pipelines with more complex stages (short and fat). This is the essence of the so called "megahertz myth". A CPU with a very high clock speed may not be any faster than a CPU with a lower clock speed. The Pentium 4 is now at 3.2 GHz yet a 1.25 GHz Alpha can easily outgun it on floating point operations.

The longer pipelines allow the x86 CPUs to attain these very high frequencies whereas the PowerPCs G4s are somewhat restricted because they use a smaller number of pipeline stages and this limits the clock frequency.

The amount of voltage the CPU can use restricts the power available and this effects the speed the clock can run at, x86 CPUs use relatively high voltages to allow higher clock rates, to boost clock speeds further, power hungry high speed transistors are used. A long thin pipeline is very fast but also very inefficient power wise. All these things add up so a 3GHz CPU may be fast but are also very power hungry with maximum power consumption rates now approaching or even exceeding 100 Watts. Intel in fact have taken to using a much lower frequency part for laptop computers than the top end Pentium 4. Yet, despite the fact it is only 1.6GHz, the Pentium M performs just as well as the 2.2GHz Pentium 4.


Bottom line: The "Pentium" style of processing takes more power than the "PowerPC" style, but tend to be cheaper. In other words, that 3GHz laptop is almost certainly faster than your 1.33 GHz Powerbook, but wouldn't last very long on batteries.

http://www.osnews.com/story.php?news_id=3997
 
Joined
Jul 22, 2003
Messages
6,999
Reaction score
187
Points
63
Location
Hamilton College
Your Mac's Specs
20" iMac C2D 2.16ghz, 13" MacBook 2.0ghz, 60gb iPod vid, 1gb nano
Mhz Myth


Thats a lot like what that video shows (except the video is colorful with pictures to make it easier for people with low attention spans (like myself))
 
Joined
Jul 22, 2003
Messages
6,999
Reaction score
187
Points
63
Location
Hamilton College
Your Mac's Specs
20" iMac C2D 2.16ghz, 13" MacBook 2.0ghz, 60gb iPod vid, 1gb nano
no problem. I always forget where I put that link. I've posted it a few times in the forums here
 

Shop Amazon


Shop for your Apple, Mac, iPhone and other computer products on Amazon.
We are a participant in the Amazon Services LLC Associates Program, an affiliate program designed to provide a means for us to earn fees by linking to Amazon and affiliated sites.
Top