The Easy Guide to CPUs

What makes a CPU good?

The easiest way to answer this question is to break-down the main parts that make up a CPU.

Clock Speed

If you’ve seen processors advertised before, you’ll be familiar with seeing clock speeds (or the clock rate) in GHz.

What this indicates is how many times per second your CPU can perform tasks. So, if your processor has a speed of 3GHz (3,000,000,000 hertz), it can perform up to 3 billion cycles a second (more is better).

Base Clock vs Max Clock (or Boost Clock)

Most Ryzen/Intel CPUs today record their clock rate with multiple figures, usually “base speed” and “max speed”/”up to”.

Essentially, CPUs today are intelligently built to only use the clock speed that is required for the tasks at hand in order to conserve power.

If you have an expensive processor and are just running Netflix, there’s no reason for the hardware to heat up and run at max capacity!

The base clock, as the name suggests, is what your CPU runs at when idling/during low intensity.

The max clock is how much individual CPU cores can climb up to in power when performing intensive tasks (e.g. gaming, rendering).

Both are important, and a higher value for either means a faster system in different circumstances (in most cases, the 2 values increase at a similar rate to each other with more expensive CPUs).

Cores

The other term you’re probably already familiar with when seeing CPUs on Amazon; a core is an integral part of buying a processor today.

Essentially, each core is its own individual processor within your CPU.

So, for example, a quad-core CPU is essentially 4 CPUs in one, each capable of performing its own tasks.

Most processors today are between 4 and 8 cores, but the full range is anything from 1 to 128.

Sounds pretty awesome right? Well, for the most part, it is!

But there is an important point to make, using quad-core as an example: 4 x the cores does not mean 4 x the power in individual processes.

In simplistic terms, having 4 cores means you can perform 4 independent operations as fast as 1 core can perform 1 operation.

If you’re trying to get 4 cores to target the same task (e.g. playing a game), then the clock speeds, IPC, and other aspects of how your CPU works for a single core will be integral too.

That’s not to say having more cores doesn’t help individual processes, many applications (including games, as we’ll discuss further below) are developed with multi-core use in mind and can utilize some of their power.

Cores are important, and the days of single-core are over (with dual-core also on its way out), but we’re just trying to stress that there is no reason to go too crazy with cores. We expect 99% of readers would see close to 0 benefits from more than 16 cores, and many will see diminishing returns past 4-8 (we break this down for each PC type further below).

Threads

Multithreading is a technology that is used by Ryzen (SMT or simultaneous multithreaded) and Intel (hyperthreading) to allocate multiple  “virtual cores” (i.e. threads) inside each core.

In simple terms, this allows cores to split up certain types of workload (e.g. when 1 thread is waiting on information to complete a task, the second thread can be busy doing “prep work” for that task).

They both share the same physical specs of the core, so real-world performance gains are usually only marginal from your thread count.

There’s good news for learners too: nearly every mainstream CPU today has 2 threads per core. Therefore there’s no significant need to focus on thread count when you’re already considering cores.

IPC

The IPC is best described as the “hidden ingredient” for what makes a CPU good, as it is often not as discussed as the more marketable specs above and below.

Despite that, it’s very important in establishing speed; IPC stands for instructions per cycle/clock.

As you might expect from the name, IPC indicates how many tasks/instructions your CPU can perform for each cycle.

This is an underutilized spec as you could have a CPU with a very high clock speed, but if its IPC is low, it will be slower than a low-clock speed CPU with notably higher IPC.

IPC is often indicated or tested in CPU reviews/benchmarks as opposed to product listings.

The good news/rule of thumb is that newer generation processors from Ryzen and Intel will provide better IPCs than their predecessors, so although this spec is integral, you don’t have to overthink it too hard.

TDP

Thermal design profile (or TDP) is how much power your CPU demands in watts (e.g. 65W).

If just one TDP figure is provided, this is nearly always the max wattage required by your CPU (under heavy loads). Sometimes listings also include the idle/base TDPs, which refer to how much power is drawn at calmer usage.

In terms of performance, TDP does not directly affect your CPU (yes, higher TDP tends to mean a more powerful processor, but this isn’t a great metric, focus on the specs above).

Instead, what TDP is good for is understanding what level of CPU cooling you need and the PSU requirements of your CPU.

It’s also the best indication of how much you can expect your CPU to increase your energy bill (higher = more) but the difference between a modest and high TDP usually won’t mean more than $5-$20 per year.

Cache

Processor cache is the onboard caching system on a CPU that is used to interact with your RAM and access frequently used information from it as required.

The cache is important, but the values between modern CPUs are going to be very similar, and any differences are going to have immense diminishing returns in real-world performance compared to clock speed, core count and IPC. We included this for completeness but would recommend most users to not worry about this spec in their buying decision.

Integrated Graphics

Depending on the model of CPU you’re purchasing, you may have a processor designed to also do the job of a GPU included.

This is more useful if you are building a very budget/basic general use PC or a smaller computer with less graphical requirements to avoid the spatial needs of a graphics card (a common example is building a home theatre PC in a horizontal case).

If you’re building a mid-range desktop or something for gaming, you’ll definitely want a graphics card over integrated graphics; an independent GPU provides much more power (having the integrated functionality may still be useful to have as a backup if your GPU has issues and you need to troubleshoot, but isn’t essential if you’re on a budget).

The same logic goes for laptops, many have integrated GPUs to save on space; this is fine if you are a general user, but you’ll want a laptop with a GPU for gaming, video editing, or longevity.

Which CPU specs are the most important?

We’ve included all the main parts for completeness, but the short answer is how good a CPU is for most users is mostly determined by a mixture of its clock speed, IPC, and core count.

If you’re confused, a great rule of thumb to follow is that the latest generation of Intel and Ryzen processors will be the best “bang for your buck” at each of their respective price ranges and contain the latest innovations in clock speed, IPC, and core counts (we’ve provided some of the best options below).