Sunday, July 17, 2011

How to buy a computer Part 1: Chosing a CPU.

You mean there's really more to buying a computer than finding the cheapest one and handing the guy money? YES!

Throughout this post, you may see some underlined links.  These are links to Wikipedia articles that explain some of the terms I use.

I've seen cases where sometimes as little as $50 dollars more spent can mean the difference between a computer that you'll hate in a year vs one that will run well for several years.

First of all, you'll need to know what you want to buy.

Right now there are 4 basic categories of PC that you can buy.
1. Traditional PC: This is a desktop computer, usually a minitower and a monitor.
2. All in one PC: This is a desktop computer with everything built in to the screen, some of these feature a touch sensitive screen.
3. Laptop: This is your standard laptop that you're used to.
4. Netbook: This is a very small laptop with usually a 10" or smaller screen.

Before even leaving the house to go to the store, make a list of what you want. Here are some things to consider:
1. CPU: This is how fast it will go, but there are many choices.
2. RAM aka Memory: The more of this you have, the more programs you have running without it bogging down.
3. Hard Drive Space: This is where you store all your programs, documents, pictures and videos. More is better.
4. Video card: Often overlooked, the video card or chip in the computer has a major impact on the score generated by the Windows System Assessment Tool.  If you want to play *any* kind of game that has something more to do than tending to farm animals, eating words, or making cakes, you should pay close attention to this.
5. Ports: Computers have a number of these, this is the place where things plug into. Some examples are USB ports where things like portable hard drives, printers, mice, keyboards, scanners and such plug into. Some other ports are things like VGA, DVI, HDMI, eSATA, 1394 (aka firewire) and even printer ports.

The CPU:

The CPU is your computer's engine.  Just like a car, an engine with more horsepower and torque will get you moving faster.

On the market currently there are two major vendors of PC CPUs. Intel and AMD.

Both have been around for a few decades and both make good CPUs, but both also make BAD CPUs.  Now I don't mean BAD as they fail easily, but BAD as in don't waste your money on them.

So lets start with BAD. These CPUs are fully functional but very slow because of a number of cost cutting measures namely the CPU cache.

These CPUs are the Intel Celeron and the AMD Sempron. These CPUs have a very small CPU cache. What is CPU cache? Well CPU cache is a small bit of very fast memory that lives inside the CPU.  It greatly speeds up the CPU's ability to access the memory chips on the motherboard.

To make it easier to understand, pretend you work at a diner and your job is to make sure everyone's coffee is full.  Your diner serves 4 kinds of coffee, regular, decaf, hazelnut and french vanilla.

Because you can only hold two pots of coffee at a time, you choose regular and decaf. You carry those with you because you know that's the most likely response to what kind of coffee the customer will want.  Because the pots are in your hand you can consider them in your cache. If you ask the customer what kind of coffee he wants and he says decaf, you have that and you refill his cup. In computer terms this would be called a cache hit.  Now the next person wants french vanilla, but you don't have that with you so you have to return back to the counter, set down one of your coffee pots and you pick up the french vanilla. This costs time and is referred to as a cache miss. You did not have what was asked for in your possession (in your cache) so you had to return to the counter (the computer's RAM) and get what was needed.

In the computer world, this happens millions and sometimes billions of times a second. So all these cache misses really add up.

Now if your restaurant somehow hired an alien from another planet that had four arms, he could hold all the coffee pots at the same time and would eliminate cache misses.

This is where the Celeron and Sempron come in.  They have small CPU caches and are very sluggish compared to their higher performance counterparts. Your computer will be constantly having to go back and forth to memory to "set down a coffee pot" and "pick up another"

Intel has also resurrected the Pentium name in a new CPU that's a little faster than the Celeron, but still not quite as good as the Core series.

Good CPUs:

Here's what makes a CPU good, large CPU cache, multiple cores and a high bus speed.

Since we already know about how cache impacts CPU speed, lets talk about multiple cores.

About 4 or 5 years ago Intel and AMD started making CPUs that had mutiple cores. A core is essentially a standalone CPU.  A multicore processor has more than one CPU in it.

Think of having more cores as having more torque.

An economy car and a Semi truck both may go from 0 to 60 in 15 seconds. But the Semi truck can do it while hauling a trailer full of elephants!

More cores allows the computer to multitask much better. As a computer starts up a dozen or so different parts of the Operating System start running. On a computer with one CPU core, all those things line up like cars on a single lane road.  With the addition of a second core, in theory, twice as many cars can reach the destination in the same amount of time.  Not because the cars drove any faster, but because there were more lanes in the road to get there.

CPUs in the Intel Core line (except for the Core Solo) all have multiple cores. AMD cpus such as the Athlon X2 and Phenom have multiple cores as well.

In a single core system, one program could potentially take over and slow everything down. If you opened the  Windows Task Manager and your computer is running slow, you may see one program using 99% of the CPU. If you had a multiple core system one program may only use 50% and you still have that other core to run everything else.

In the Intel Core series there is the Core (no longer made) Core 2 (may no longer be made) Core i3, Core i5 and Core i7. For them think of it as Good, Better and Best. Core i3 is only typically in basic systems that are a little better than the Celeron. i5 is for decent mainstream systems and i7 is for high end systems.

(I apologize to any AMD fans out there as since my experience is mostly from the business side, Intel is the major player there, so my specific knowledge of AMD specs is a little lacking compared to Intel)

If you are looking at two computers that are about the same price and the features are pretty close but one has an AMD cpu and one has an Intel one then you can compare them using the Windows System Assesment.

You can access this by clicking on the Start "orb" (bottom left corner of the screen), Right click on "Computer" and select "Properties".

Now click on Windows Experience Index.

In most cases you'll see something like this. In this example lets say the computer on the left got a processor score of 6 and the computer on the right got a 6.5. As far as basic ability to compute things, the computer with the 6.5 should be faster. However be mindful of the other scores as well. Things like graphics can have a major impact on your computer. And we will talk about that part later.

I hope you're enjoying this blog, and if you need PC help in the Fort Worth/Keller/Watauga/Haltom City area just shoot me an e-mail at

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