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How Powerful a CPU do You Really Need?


For decades we have been conditioned by computer hardware and software vendors and computer salespeople to buy faster, more expensive CPU's than we really need. One of the conditioning techniques has been the incitement of fear through the threat of obsolescence. Although Moore's Law was true for decades, it is not true today. The good news is that since Moore's Law no longer holds, the threat of computer obsolescence is now a mostly an idle threat, and judging by the slow decline in computer purchasing, at least some people are beginning to realize this. The bad news is that, as a result of the decades-long reign of Moore's law, the vast majority of software applications that we use today are very inefficient.

In the mid 1980's many people used a word processor called Wordstar, which ran fine on a Intel 8086 CPU. Today, I occasionally have difficulty running the Microsoft Office word processor on my Dell Latitude E6220, which has an Intel Core i5 2540m CPU. Why does word processing now require CPU's that are millions of times more powerful than those that were used thirty five years ago? The answer is simple: inefficient word processing software. Yes, today's Microsoft Office word processor has many more bells and whistles than Wordstar did, but most people rarely or never use those bells and whistles. I would be willing to bet that people who would argue with my statement about software inefficiency have never written software for a living. Nevertheless, most of the time a person's choice of software is the single biggest factor in determining how powerful his CPU must be.

A strong interdependency exists between a software application, the operating system, and the computer hardware. Most often, the oldest version of a particular type of software that you can run on your computer will be determined by the operating system you can run on your computer. The oldest operating system you can run on your computer will in turn be determined by the drivers that are available for the hardware in your computer. So, if you intend to run really old software, you may need to run it on a really old computer. And this is certainly one way to go if you can't afford to spend much on a computer, and you don't need to run any newer software. This is how many people are still getting away with having fifteen-year-old computers with Windows XP as their only computers.

Another option that has come along recently is operating system emulators. We now have programs like Dosbox that allow us to run DOS programs on a modern computer with a modern operating system. This is another way to go, assuming the emulators do not consume too much of the CPU's capability. If you want to go this way, you will have to try this and see if it works for your software application.

The next biggest factor in defining CPU processing requirements is the type of application. For example, playing a high definition video file is inherently more CPU intensive than running an efficient word processing program--even though word processing programs can be made inefficient enough to require more powerful CPU's than those required to play high-definition videos. I am aware that these days CPU's have video co-processors, so the subject is more complicated than I want get into for the purposes of this article. I think it is sufficient here just to say that different types of applications require different CPU processing capabilities.

The last major factor that one must think about when considering a computer purchase is the efficiency of the hardware. Hardware efficiency can vary significantly from computer to computer due to various bottlenecks like bus speed, hard drive or SSD drive read/write speeds, RAM speed, and many, many other factors not related to CPU processing capability. Unfortunately, it can sometimes be difficult to get an idea of the effects that hardware efficiencies will have on the performance of a specific piece of software without actually sitting down with a particular computer and running that piece of software on it. The one bright spot in this regard is that many online reviewers now publish the results of bench testing with software that runs computers through semi-real-world applications. So, you can sometimes get an idea from their testing whether a particular computer is powerful enough for your applications.

An example that I've used in the past to help illustrate the significance of hardware efficiency is a used laptop I bought around 2010. This laptop, which I will not identify, was a 10.1" laptop with an atom processor. After I bought it, testing revealed that the read speed of the hard drive was only two megabytes per second. This is despite the fact that the hard drive was capable of being read at least twenty times faster. I eventually determined that the slow read speed was due to the fact that there was no sata driver available for the hard drive, forcing the BIOS to run in IDE emulation mode. This is an extreme example of an unnecessary "hardware" bottleneck (more correctly, a firmware bottleneck), one which was never corrected by the manufacturer despite the fact that this model of laptop was sold to computer consumers for at least five years. This would not have happened on a business grade laptop; hence, my continued insistence that most people should be buying business laptops, instead of consumer grade laptops.

Anyone who intends to minimize the cost of his next computer purchase must decide what types of applications he wants to run and the most efficient software that can be used to run them. Since many people lack the perspective obtained from thirty or more years of using computers every day with a wide variety of applications, this can potentially be a very difficult thing for them to do. Therefore, in this article, I will suggest to you some methods and rules of thumb to go by to give you hopefully a better idea of what CPU's you can live with, rather than simply buying whatever computer some reviewer or salesperson tells you to buy. So, let's get started.

The easiest to use indicator of CPU performance that we have at our disposal is probably the Passmark CPU performance benchmarks available online here. Passmark has a very long list of benchmark scores for nearly every CPU made in the last twenty years or so. Below are the Passmark scores for CPU's in some of the computers that I own:

CPUPassmark Score
Intel Atom N270268
Intel Celeron M 410315
Intel Core Duo T2400795
Intel Core 2 Duo T9600   1928
Intel Core i5 2540m3782
Intel Core i7 3720QM8331

A CPU that has a Passmark score double that of another has a processor that is roughly twice as powerful as the other. This is a bit of an oversimplification for a number of reasons. One is that the Passmark score takes into account multiple CPU cores, but software may only use one core. Despite its inadequacies, the Passmark score is the metric that I use for CPU performance when I consider what computer to buy for myself. So, I can sort of say that the Core 2 Duo T9600 in my Dell Latitude E6500 laptop (which I bought used for $55 on Ebay in 2016) is about six times as powerful as the Intel Celerom M 410 in my Compaq Presario V5000 laptop. Now that you have an indicator of relative CPU performances, let's consider what CPU performance requirements are necessary to run various types of software.

Surfing the Internet

This is one of the main applications that almost everyone has in mind when they buy a computer. Unfortunately, there are so many different internet browsers that it is difficult to generalize CPU requirements for them. But I will tell you that newer browsers require significantly more CPU performance than older ones. Unfortunately, the newest browsers also give you the most protection from threats on the internet. They also subject you to the most corporate monitoring. Most of the time, I surf the internet with java scripting turned off, and I don't use the most recent browsers, but they aren't too old either. Today, I'm using Firefox version 48 and Chrome version 52, if that helps. One of the benefits of having java scripting turned off when I surf the internet is that it reduces the CPU performance necessary to surf smoothly. Another is no annoying animated advertisements. Turning of java scripting allows me to use my Dell Latitude E6500 to surf the internet easily. In early 2016 I switched to this laptop, because my Compaq Presario V5000 was freezing up while surfing. So, this means that for the way I surf the internet, I know that a computer with a CPU Passmark score of 1928 works just fine, but a computer with CPU with a Passmark score of 315 is not nearly good enough. Some other CPU's with Passmark scores around 1900 are: Intel Pentium 3805U, Intel Celeron 2950 M, intel Atom x7-Z8700, and AMD Athalon II X2 B26.

One thing I should point out is that there is a general misconception about webpage loading speeds. Most often, if you are using a broadband internet connection and a newer computer with sufficient RAM, the speed at which a particular webpage loads has more to do with the web server than with the speed of your computer. Many servers are trying to do too much--send too many pictures, videos, and javascript files, and run too much code. The result is that they are slow, and this is either the fault of the webpage designer or the web hosting company that is trying to run too many websites on the same server. Both parties should know better. This means you shouldn't buy a new, fast computer with the expectation of getting nearly instantaneous webpage loads.

Word Processing

As I said previously, there is a wide variation in the requirements for different word processing software. Microsoft Office has the most CPU intensive word processor of any I've used. Other word processors that are less CPU intensive are in LibreOffice, FreeOffice, and OpenOffice. Of these three, OpenOffice's word processor is the most CPU intensive, and FreeOffice's is the most compatible with the Microsoft Office word processor. I've not had any problem running any of these three on my Dell E6500 laptop. "Word", the word processing program that comes free with Microsoft Windows is significantly less CPU intensive than any of these three. My guess is that you could probably get away with running the current version of Word on a CPU with a Passmark score of 300, assuming that you could get the current version of Windows to run on it, which is very doubtful.


Email is not CPU intensive, so any processor should work. That being said, there are probably a couple of email programs out there that are CPU hogs. You don't have to use them.

Playing Standard Definition DVD's and Video Files

If you are still playing standard definition DVD's on your computer, you should be able to get by easily playing a DVD on a computer with a CPU Passmark score of 300. I know this is the case with my Compaq Presario V5000 (CPU Passmark score: 315). Standard definition video files require about the same CPU capability as standard definition DVD's. There are, however, video file players that are less efficient than the rest. Avoid these if you have an older, less powerful CPU. The video player I use most of the time is the VLC media player. The real issue with playing DVD's on older, less powerful CPU's is that you have stuttering (frame dropouts).

Playing Higher Definition DVD's and Video Files

Although I don't play many of these, I can give you a rule of thumb. Doubling the amount of data that is passing through your CPU per second requires a CPU with double the Passmark score. So, if a standard definition video file (720 x 576 pixels) plays fine on a CPU with a Passmark score of 300, a 1920 x 1080 video would require a CPU with a Passmark score of about 1500. This is oversimplified, because it doesn't take into account that most CPU's now have video co-processors, also known as GPU's. You can find GPU Passmark benchmark scores here. Many recent Intel CPU's have Intel HD 3000, HD 4000, HD 4400, HD 4600, or HD 5000 GPU's, with Passmark GPU scores between 314 and 711.

Netflix and other Streaming Services

I've been able to play Netflix low resolution videos, which I think are around the same resolution as standard definition DVD's, just fine on my Dell Latitude E6500. I've not tried higher resolutions, but the rule of thumb that I gave above for playing video files should apply here. I've also run several other standard definition streaming services without a problem on my Dell Latitude E6500.

Video Transcoding

This is very CPU intensive, so the faster your CPU, especially your video co-processors, the less time it will take to transcode videos. CPU's with lower passmark scores will work just fine, but they will take a long time to transcode a movie. It takes nearly four hours to transcode a standard definition DVD movie with my Dell Inspiron E1505, which has a core Duo T2400 CPU (Passmark Score : 795). It takes about an hour with my Dell E6220 (CPU Passmark score: 3782).

Operating Systems

It should be well-known by now that, despite Microsoft's marketing promises, each version of Windows is more CPU intensive that the previous version. CPU requirements for Windows are available all over the internet, so I won't go into this here.

I will say that versions of Linux that come out at the same time as a particular version of Windows tend to be slower than that version of Windows. This depends to some extent, however, on the Windows manager that the distribution of Linux is using. For those of you who are unaware, a Linux distribution is a particular collection of Linux code that is bundled together and is designated by a name, such as Ubuntu, Lubuntu, Mint, Red Hat, etc. The version of a distribution is the specific collection of Linux code for that distribution that is bundled together on a specific date. Linux versions are designated by numbers, for example Linux Mint 16.0, Linux Mint 17.2, etc. Linux is touted as an operating system that will run on older, slower CPU's. I've often found that not to be true--unless you go to older versions, assuming you can find them. The problem with older versions of Linux is the same as with older versions of Windows, the lack of compatible hardware drivers for newer hardware. You have to try a specific version of a specific distribution of Linux to really know if it will run well on your specific computer.

Video Games

These days, the performance of a video game on your computer will depend much more on the GPU than the CPU. It's not that CPU performance is irrelevant; it's just less relevant than the GPU. Fortunately, in additions to a particular game's published system requirements, there are many websites that will give you an idea of what hardware is required to play the game. These websites will be of far more help to you than I can be here.

Other Software

Aside from the 32/64 bit processor problem, the only real issue with older, less powerful CPU's is that they tend to freeze up on some applications when then they hit 100% CPU usage. Unfortunately, I don't know specifically why they freeze at 100% CPU usage. On most applications--like compiling code, video editing, any most other applications that don't have to run in real time--older, slower CPU's will get the job done. They may just take much longer to get the job done. With these non-real time applications, the limits of your patience determines how slow a CPU you can stand to use. So, if your budget is limited and your patience is high, you may be perfectly happy with an old, used laptop running a Core Duo CPU. If you have little patience, or you need to be productive at work, you may need the latest Core i7 or Core i9 CPU.


There are three main factors that determine the capabilities of the CPU that you will need to have in your next computer: the age or generation of software you need to run, the type of application, and the efficiency of the computer hardware. A good way of comparing the performances of different CPU's is the Passmark benchmark score. As explained above, some types of software, like DVD players, must run in real time; therefore, you will have to run them with a CPU of a certain capability or greater. But, most non-real time software can run on older, less powerful CPU's. So, older, less powerful CPU's may be an option for you if you have more patience than money.

Related Articles:

When Buying a Computer, More Knowledge Equals Lower Cost

Know What You Need Before You Buy a Computer

How to get a Cheap Laptop


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