On the surface, it seems simple: Pick the fastest processor you can afford for your needs?
The hidden assumptions in that seemingly straightforward piece of advice are the killer, though. The words fastest, afford, and needs are too general for this to be really useful advice.
On top of that, you´ll want to balance the overall platform needs of your PC. Buying a really fast, high-end CPU may mean skimping on memory, which can substantially reduce the perceived performance of a system. If your PC is constantly swapping chunks of memory out to the hard drive, then that hot-rod CPU will spend most of its time idling.
So let´s try to define some clear criteria for choosing the correct processor for your PC. Even if you´re not building a PC, you may be contemplating buying one from one of the many build-to-order manufacturers. This guide can help you choose the best processor for your system.
What´s the Goal for the System
Every system has a purpose. Will the system be primarily used as a family web browsing and word processing system? Is it mainly for capturing, editing, and creating video content? Are you planning on using the system as a repository for your family´s digital photo collection? Is it a purely work-oriented PC that will be connecting via VPN to a corporate network?
Try to be clear about developing an overall goal for your PC. If the PC is to be used primarily as a shared family resource for homework and web browsing, then don´t try to build a killer gaming machine. Consider the overall goal for the system before choosing the CPU. You may end up wanting to pay a little less for a lesser processor, and invest a little more in a bigger hard drive.
Look at Your Usage Pattern
Most CPU guides talk vaguely about choosing your CPU based on your applications. We feel pretty strongly that your usage pattern may be more important than the applications themselves.
For example, you´ll typically hear advice that a system used mainly for office tasks really won´t need a beefy CPU, whereas one used for digital photo editing may need substantial processor resources.
In the harsh light of day, though, this may not be the case. A power office user may have several web browser windows open, have a word document up for editing, be referring to several Acrobat files for reference and be creating a PowerPoint slideshow as a companion piece—all at the same time.
Someone merely collecting digital snapshots for the family photo album may simply be capturing pictures "as is" from a digital camera and uploading them to a web site.
Which usage model do you think would be more demanding?
Note, however, that once you get used to having more CPU resources available, you´ll start doing more stuff. In other words, your usage pattern will change. It´s difficult to predict exactly how your pattern will change, so don´t get an even more expensive CPU in anticipation of your usage pattern becoming more demanding.
Consider Your Applications Mix
We´re not suggesting you should ignore the actual applications you´re running. After all, if you´re an artist working inside 3dsmax a substantial portion of your time, you´ll benefit from more CPU (and probably more of everything, including memory.)
Most users, however, are not single applications users. That´s why it´s important to consider the overall mix of applications. You may have one very demanding application you use infrequently, so don´t let that be the sole guide as to your CPU needs.
A mix of moderately demanding applications can tax a processor even more than a single intensive application, particularly single core processors. So understanding your applications mix will make a big difference in choosing what CPU will work for you.
Understand Your Applications
Do you know how your app works?
It´s pretty easy to figure out that Word uses less CPU horsepower than Photoshop, for example. On the other hand, if you´re a veteran Photoshop user, you know that more memory may help more than upgrading your CPU, or that adding a second hard drive just for the Photoshop swap file also can make a big difference.
Even applications in similar arenas, such as PC games, may have differing needs. A first person shooter like F.E.A.R. may well benefit more from a graphics card upgrade, while Supreme Commander will eat any CPU cycles you throw at it.
So take the time to learn a little about how your most common applications work under the hood. You´ll reap benefits, not only by being able to choose the best processor, but also by being able to tweak your system and application appropriately for best results.
Take a Look at Background Tasks
Are you a Windows XP or Windows Vista user? Take a look at your task bar. Mine has eight icons representing lightweight apps, all of which are useful or necessary.
Try taking a look at task manager as well. There are often scads of applications and services running in the background. Many are idle, but others tend to be constantly sucking a few CPU cycles.
You can, of course, permanently shut down unneeded services. But knowing what your system is doing when it´s idle can help you gauge your needs. If your one of those aficionados of peer-to-peer computing, apps like Bittorrent or Folding@Home may use some CPU cycles as you keep them live.
Background tasks won´t be a primary driver of CPU choice, but you also want to be sure to minimize the CPU hit by those tasks.
What Do Other Users Need?
You may not be the only user of your system.
This may be by intent, if you share your PC with others, and use Windows Fast User Switching. Or it may be a background chore, if you´ve got files on your system you share with the family, like photos, videos, or music.
If you´ve got other users with their own user IDs, you may want to consider their needs. Maybe all you do is write an occasional email, do a little checkbook balancing, and surf the web. But maybe your spouse is a heavy user of photo editing software, and your child is into PC gaming. Their needs may dictate the best processor for your system rather than your own needs.
It´s not always just about you!
Examine Your Existing Infrastructure
Perhaps you´re currently running an Athlon 64 3000+, in a Socket 939 motherboard, and you don´t want to replace motherboard and memory. Or maybe you´re running an older Socket 775 board using an Intel 915 chipset and a Celeron processor. Both those cases will limit your choices.
In the case of the Socket 939 system, you´ll be able to upgrade to a dual core Athlon 64 X2, but those Socket 939 CPUs are becoming increasingly rare. If you´re running an Intel 915 motherboard, dual core is not likely to be in your future.
There comes a time, of course, when you do need to bite the bullet, and perform major surgery. It becomes a cost/benefit tradeoff -- when do the limitations of supporting older hardware outweigh the cost of moving to newer technology? It´s something to consider when you´re planning your CPU upgrade.
Plan for the Future
If you don´t upgrade your hardware with the frequency that we do (which means almost constantly), you should consider this: As new versions of your favorite applications emerge, they tend to devour more processor cycles than last year´s versions.
Blame it on bloat if you must, but if you´ve just got to have the added features and functionality offered by Office 2007, it might need more horsepower than Office XP. Similarly, if you´re planning on making that move to Windows Vista, bear in mind that it will demand more from your system than Windows 98.
When you plan your CPU purchase, remember that the games, applications, and utilities of tomorrow—when you might not be ready to drop in yet another new CPU—might make you wish you´d gone with more processor muscle.
Don´t Forget the Electric Bill
Increasingly important in this era of concerns over climate change is power usage. You may very well be able to afford that badass Core 2 Quad, which is rated at 125W TDP, as well as dual GeForce 8800 GTX cards. But you´ll need a 650W or better power supply to drive the system. Maybe, just maybe, your gaming desires can be adequately addressed by a single GeForce 8800 GTS and a Core 2 Duo E6700, both of which draw substantially less power.
By itself, a 125W TDP processor doesn´t draw that much more power than a 65W processor, but those high end processors often dictate what else is being built into the system. Think about your electric bill before building a system that requires an 850W PSU.