If you’re building a gaming PC on a budget, you’ll probably want to start off by choosing a video card. Everyone else can start with the central processing unit (CPU), or processor, the “brain” of the computer that, well, processes all the instructions it receives from the software you run and the other components you have installed. Because of the considerable difference it will make in how well you run every program on your PC, paying particular attention to its capabilities is crucial.
What to look for?
Number of cores. Back when every CPU only contained one processing unit, or core, clock speed (see below) was the easiest way to measure performance. But practically every processor today is a multicore CPU, and the more cores a chip has, the more it can accomplish at once (if it’s supported by the software). Most common are two (dual) and four (quad) core CPUs, though six- and eight core CPUs are becoming more visible on the market.
Number of threads. Most processors today, particularly from market leader Intel, can simultaneously operate two processing threads per core (Intel calls this technology hyperthreading), effectively doubling your core count. Because not every processor supports this, check that yours does if you expect to be running a lot of multithreaded applications.
Clock speed (operating frequency). This is the frequency at which each core in a CPU runs, or the number of cycles it is able to execute per second. The higher the number, the faster CPU will generally be per core. These days, clock speed is measured in gigahertz (GHz), or billions of cycles per second.
Cache (L2 or L3). A processor uses memory installed in the chip itself to store and speed up operations before utilizing external system RAM. This onboard memory is stored in one or more caches, which are identified L2 or L3. More powerful processors will be equipped with larger caches.
Socket type. CPUs come in different sizes and are identified by the kind of socket they plug into. (For example, Intel’s most powerful current chips use the third revision of the LGA 2011 socket.) You’ll need this information to determine what motherboard to buy.
Manufacturing technology. Every year or two, processors get thinner and more power-efficient. Knowing a chip’s manufacturing technology (measured in nanometers, or nm) will give you some insight into its capabilities, but is not strictly necessary.
Cooler. Most processors come with a fan rated for their specific speed and estimated heat output; unless you’re planning to overclock your computer or otherwise put it through particularly traumatic paces, you probably don’t need to buy another fan or liquid cooling system. (And for that reason, we’re not going to dwell on the question here.) But if you do decide to go with an aftermarket solution, or if you choose a high-end CPU that doesn’t come with its own fan, make sure that the cooler you get is designed for the family of processor you have.