Home > Computing, Opinions > Gigahertz Just Bug Me: The Story of How Gabe Will Rant About Consumer Microprocessor History In Response To Consumer Ignorance

Gigahertz Just Bug Me: The Story of How Gabe Will Rant About Consumer Microprocessor History In Response To Consumer Ignorance

So have you ever spoken to a person about computers and had them brag about their new “3 gigahertz processor”? I sure have. And it’s aggravating.

Take a look at this. On the left is the “clock crystal”, which sends out pulses that synchronize the components of your computer. Everything in a computer has to synchronize to some base frequency, or you’ll lose performance as components will drift out of sync and therefore have to wait for pulses in order to do the basic bit-level operations that a computer does. The thing on the right is the Phase Locked Loop generator, which I’m not as familar with. It seems to regulate the processor’s voltage based on the clock crystal. Or is it the other way around? I’m not nearly as good with electric engineering as I would need to be to perfectly understand this.

But I disgress. If you’ve ever looked at a CPU, you’ll find they’re much bigger than the clock crystal. You’ll also find the amount of jargon you can use to describe a CPU is much greater – pipelines, caches, instruction level parallelism, cores, thermal design power. The point here is that you can not describe a CPU in terms of clockspeed alone. The clock crystal is the only computer hardware that I know of that can be described solely in terms of clockspeed, and you know how much work you can get out of a few billion uniform pulses per second?

That’s right. Nothing at all. So do me a favor – the next time that someone boasts about their processor on clockspeed alone, make sure they realize that they can’t do much with merely a clock crystal. A stupid joke, but it might raise awareness of these CPU differences.

With this all in mind, people need to consider that different CPU architectures perform differently at the same clockspeeds. This inability to do such prompted our giant friend Intel to design the “Netburst” architecture in the Pentium 4/D CPUs. They realized this microarchitecture blindness of the people, and therefore designed a processor entirely around achieving massive clockspeeds. The ancient documents claim that Netburst was supposed to scale into the 5-10 Ghz range, but suffice it for now to say they didn’t. When the first Pentium 4 came out at 1.5 Ghz, they ended up slower than AMD’s competing Athlons (at 1.2 Ghz) and even the Pentium III (at a “measly” 1 Ghz). The Pentium 4 continued to fail to compete with these lines until three things happened:

1. The “Northwood” revision of the chip improved performance per clock cycle with improvements that are probably too technical to describe briefly in this post,

2. Moving to a smaller semiconductor fabrication process allowed Intel to ramp up the clockspeeds as promised, from starting at 2 Ghz all the way up to 3.4 Ghz,

3. Which means that AMD, with less resources to throw at engineering, and a design that WASN’T built for mass clockspeeds, eventually were unable to raise their own clockspeeds fast enough to compete with Intel and therefore had to look towards new options to improve their performance, such as adding 64-bit extensions, and eventually producing dual-core dies.

Later, Intel hit a brick wall in clockspeed scaling at 3.8 Ghz @ 90 nanometer processes – it simply too far too much cooling technology to keep the CPU alive at such rates. So they had to do the same things just to keep Netburst “competitive” with AMD. In the mean time, they ended up scaling their “Pentium M” CPU (which evolved from the Pentium III)  up to the desktop and server sockets, and that’s how we got the Core 2 processor, and later, the “Nehalem” based i3/i5/i7 processors, which perform much better than the Pentium 4 ever did, and are almost up to the clockspeeds that Netburst achieved. This is great if you use your PC for heavy duty work, like 3D rendering or certain buisness applications, but there’s still some time before you actually NEED these processors for gaming, in which most Northwood based Pentium 4s will allow you to play the latest games.  Just don’t complain when someone’s 2.66 Ghz Core i5 outperforms your 3.8 Ghz Pentium 4.

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