The Need for More than Speed: CPU Tips for PC Buyers

In the world of digital devices, more - whether it be megapixels or megahertz - was always better. Until it wasn't.

Most of know that digital cameras have gotten so good that we don't need to think about megapixels at all. And all of us PC enthusiasts used to obsess about CPU speed, measured first in megahertz and then gigahertz. But as you may or may not know, the speed of a microprocessor is no longer the best measure of the value you'll get for your money.

Now that Intel, the maker of the majority of CPUs that go into desktop and laptop computers, has recently introduced a new line of chips, this is a good time to brush up on your knowledge of those finger-nail sized dynamos. It's even more important to penetrate the marketing buzz and know what's really going on under the hood if you're about to buy a new computer.

So here's an FAQ that will tell you what you need to know.

Does it matter who makes the CPU in my computer?

The answer to that question changes every couple of years. The two major makers of microprocessors, Intel and AMD, tend to leapfrog each other every few years.

At the moment, Intel's new line of chips, the i3, i5 and i7 (you may have heard them referred to as Sandy Bridge) are clearly superior to AMD's offerings on the higher end. At the low end, AMD offers good value, and if you're looking to save money go with a computer carrying that company's processor. AMD will unveil its own new line of high-end chips in a few months, and the game will continue.

Are Intel's new chips really better than the old, or is this just more marketing hype?

Good question. To get an expert answer, I contacted Dean McCarron, the principal analyst of Mercury Research, who has followed chips and chip design closely for a couple of decades.

"They are," he says. "The new architecture is significantly higher in performance than its predecessor." But you'll note they aren't significantly faster, a paradox I'll explain in a bit.

What's better about them?

They are more efficient, which is to say they get more work done in the same amount of time. Speed in CPU terms is analogous to the ticks of a clock. More speed means that the clock is ticking faster. As the clock ticks, the chip handles instructions, mathematical algorithms that when translated tell the computer what to do. It used to be that the faster the clock ticked, the better off you were.

Speed of the processor was a very big deal, and computer makers would use that number to hype their machines. But after a while, increases in raw speed no longer led to increases in efficiency. As chips got faster, they used more power and generated more heat, without getting much more work done. In essence, Intel and AMD reached a point of diminishing returns when it came to clock speed and looked for other ways to increase the efficiency of their chips.

Without going into lots of geeky detail (but if you want to know more, here's an excellent discussion of the issue), the new generation of chips get a lot more work done during every tick of the clock, says McCarron, and that's what you need to care about - along with the ability to render graphics.

What about graphics?

PCs handle graphics in two different ways. They can be integrated into the processor, or they can be handled by a separate, or discrete, graphics card. If you're a gamer, or do a lot of demanding, graphics-oriented work such as CAD or serious video editing, then spending an extra $100 or $150 for a discrete graphics card is a smart investment, McCarron advises.

But if you're mainly using your computer to surf the Web, use Office-like applications and stream video you'll be fine without a graphics card. However, some chips with integrated graphics capability do a better job than others, and that's where the Sandy Bridge family stands out, says McCarron. On average, graphics performance of the new line of chips is about twice that of the earlier generation, enough of a difference to be noticeable in the real world.

So don't worry about the advertised speed of the chip?

By and large the answer is no. If you're buying online, computer makers like Hewlett-Packard and Dell will let you configure your PC. Spending more for a slightly faster processor isn't necessary. If you have some extra budget, add more memory and a faster (7500 rpms instead of 5500 rpms) hard drive, options that really will pay off in better performance.

How do I know which chip to buy?

It's a little confusing. The chips we're talking about are the newest generation of Intel's core family of processors, and they are called i3, i5 and i7. Annoyingly enough, the previous generation had the same monikers so you'll have to look a bit further.

The new generation has a four digit model number; for example i3 2310M (the M stands for mobile and I'm not counting it as a digit) or i5 2520M. The older versions have 3-digit names. Before long, the older chips will no longer be installed in new PCs so the issue will go away. But for now, check the full model number.

Finally, it's worth noting that the i5 gives you more performance than the i3, but not as much as the i7, which - for now - is the hottest Intel chip you can buy.

San Francisco journalist Bill Snyder writes frequently about business and technology. He welcomes your comments and suggestions. Reach him at bill.snyder@sbcglobal.net.

Follow Bill Snyder on Twitter @BSnyderSF. Follow everything from CIO.com on Twitter @CIOonline.

Read more about consumer it in CIO's Consumer IT Drilldown.

This story, "The Need for More than Speed: CPU Tips for PC Buyers" was originally published by CIO.

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