Buying a CPU is often much more than a necessary upgrade — it can determine the platform you'll stay on for the foreseeable future, and the features you'll have access to. This is why it's important to spend some time finding the details about the CPU you're planning to buy. The number of specifications you'll find online might overwhelm you, especially if you're new to PCs. So, I've condensed everything down to the 5 specs you should care about, and 3 that you can ignore.

I won't list basic stuff like socket type and supported chipsets, as a Google search or PCPartPicker will point out any compatibility conflicts. While things like CPU cores, cache, and TDP are useful, you don't really need to worry about clock speeds and unlocked multipliers on modern CPUs.

7 Number of cores

First things first

The number of cores is one of the easiest modes of segmentation used by both CPU manufacturers and consumers. Everyone understands that, generally, a 16-core CPU will be faster than an 8-core CPU, which will in turn be faster than a 6-core chip, as long as you're comparing parts from the same microarchitecture.

When you're in the market for a new CPU, you probably have an inkling about what you'll use your PC for. A 6-core CPU is enough for modern gaming, while CPUs with 8 cores and more are usually preferred by productivity users and enthusiasts. The higher the core count on a CPU, the more instructions it can process in parallel, benefitting programs that are designed to utilize multithreaded horsepower.

Multithreading allows an individual core to behave as two separate cores by handling two threads simultaneously. More threads usually mean more performance, but as Intel's Arrow Lake CPUs have shown, the absence of hyperthreading didn't stop the chips from delivering strong productivity gains. Workloads such as gaming don't scale much beyond 6 cores. And 4-core CPUs were popular years ago, but today, they're only good for those building an entry-level system or one that prioritizes low-power operation, such as an HTPC.

6 Clock speed and IPC uplift

The newer, the better (usually)

The clock speed of a CPU tells you the number of cycles it can execute in a second — essentially how fast the transistors on individual cores can perform the requested operations. While it's an important metric, clock speed alone isn't enough to judge a CPU's performance, especially when comparing CPUs across generations and architectures. You should see it in conjunction with IPC or the instructions per clock is the number of instructions a CPU can execute in a clock cycle.

While clock speeds don't usually increase much from generation to generation (in recent years), the generational IPC uplift is usually significant. With advancements in microarchitecture, CPU manufacturers like AMD and Intel can deliver strong IPC gains generation over generation. However, it's important to note that high IPC gains don't always deliver an equivalent performance boost in gaming or productivity applications.

For instance, AMD's Ryzen 9000 CPUs boasted a 16% IPC uplift over Ryzen 7000, but the real-world performance increase was only around 5–10% in gaming. The underlying architectural improvements are what actually matter. This is why consuming third-party benchmarks is important before making a purchase decision. Real-world performance will tell you the net performance gains delivered by a new CPU over an older one — in the workloads you're interested in.

5 Cache

Oft-ignored, but can be a game-changer

Cache is a small amount of blazing-fast memory soldered directly onto the CPU die, allowing the processor to speed up data retrieval. Since cache is orders of magnitude faster than RAM, a greater CPU cache can greatly accelerate certain workloads on your PC. CPUs have three types of cache: L1, L2, and L3. L1 is the fastest and L3 is the slowest, but you should still focus on L2 and L3 cache when comparing CPUs.

Each CPU core has its own L2 cache, but shares the common L3 cache pool, and both of them are instrumental in performance. For instance, AMD's Ryzen X3D CPUs utilize huge amounts of L3 cache stacked vertically to speed up gaming performance. Chips like the Ryzen 7 9800X3D and Ryzen 7 7800X3D are the fastest gaming CPUs in the world, thanks to this innovative L3 cache. Most CPUs have 6-12MB of L2 cache and 24-36MB of L3 cache; Ryzen X3D CPUs feature up to 16MB of L2 cache and 128MB of L3 cache.

4 PCIe support and lanes

Some deficiencies can go unnoticed

The PCIe generation supported by a CPU determines the maximum bandwidth available to components like the GPU and SSD. While the maximum bandwidth is rarely utilized, the PCIe support still gives you an indication of how long you can expect your CPU (and the platform) to last. Currently, we have different generations of CPUs supporting up to PCIe 4.0 or PCIe 5.0 interconnect lanes.

While Intel CPUs starting with the 12th Gen Core series support PCIe 5.0, AMD only migrated to the newer standard with its Ryzen 7000 CPUs on the AM5 socket. The bigger concern when reading about the PCIe support is the number of lanes your components have access to, depending on the CPU you choose. While most modern chips will allow 16 lanes (PCIe 4.0 or PCIe 5.0) for the GPU, some processors like the Ryzen 7 8700G allow only a PCIe 4.0 x18 link for the GPU.

If you're buying such an APU for entry-level gaming, and thinking of installing a dedicated GPU later, you'll only have access to 8 PCIe 4.0 lanes. The performance difference in games and other programs will be very small (often negligible), but you might not want to invest in a CPU that limits the performance of a powerful graphics card. If you're planning to use the system for 5 to 7 years, it's better to opt for a CPU that gives you full access to all modern technologies.

3 TDP

Gets more attention than it deserves

The TDP or Thermal Design Power of a CPU measures how much heat the chip can produce under normal operation. A higher TDP, such as 180W or 250W, usually means that the CPU is capable of consuming more power, and will get way hotter than a processor with a TDP of, say, 65W or 125W. It's not a hard measure of the maximum power your CPU can consume under load, but rather a helpful suggestion about what kind of CPU cooler you should buy.

This makes TDP a less-than-useful metric when buying a new CPU. Sure, the 253W TDP of a Core i9-14900K might tell you that you need a 360mm AIO cooler, but the Raptor Lake chip is known to blast way past 250W under serious loads, at which point even high-end AIOs aren't able to tame it. So, it's more useful to find out about the actual behavior of a new CPU or generation to make your decision about the necessary cooling hardware (or whether you should even buy the CPU in the first place).

Today, you can basically ignore the TDP rating of a CPU, and simply make your choice of cooler based on your preference. Air coolers can handle pretty much any mainstream CPU these days, so opting for an AIO liquid cooler is more of an esthetic choice. AIOs are also relatively more silent than smaller air coolers, so that can also be a consideration.

2 Integrated graphics

Doesn't matter for most people

If you're building a PC without a dedicated graphics card, you already know that you want a CPU with integrated graphics. You'll probably opt for an APU from AMD for some impressive 1080p gaming in the latest titles, and call it a day. On the other hand, if you want nothing to do with integrated graphics, you'll pick a CPU and graphics card based on their gaming benchmarks, so whether or not the CPU has onboard graphics, doesn't matter. Integrated graphics on a CPU can help diagnose problems with your dedicated GPU, but that use case alone shouldn't be a huge reason to care about this specification.

1 Unlocked multiplier

Who overclocks their CPU anymore?

In case you didn't know, overclocking your CPU doesn't make sense anymore. Modern CPUs are substantially more powerful than older models that used to deliver significant gains from overclocking. Besides, manufacturers are used to tuning CPUs to offer close to their maximum performance right out of the box. Any clock speed gains you're able to achieve might not even improve your FPS in GPU-intensive titles.

All you'll be left with is a CPU that runs hotter, consumes more power, and offers little real-world gains. Hence, you can stop caring about whether your CPU is "unlocked" or not before buying one. The absence of an unlocked multiplier on CPUs like the Core i5-14400 doesn't make them bad; other reasons might do that, but that's not the point here. Overclocking your CPU is a time-consuming process that delivers little benefit to most users, and should no longer be a factor in the buying decision.

Choosing a CPU is much more than reading the specs

Today, deciding which CPU to buy often comes down to watching or reading reviews. Specs like core count, clock speed, and cache might determine gaming and productivity performance, but most users don't read the spec sheet to reach that outcome. Of course, word of mouth, local availability, and brand familiarity still matter, but I believe the average PC builder today trusts online forums and reliable publications to make purchase decisions.