BattleNub's ByteSized BlogGuide to Comparing CPUs for Your PC Build
Message boards dedicated to PC building are often overflowing with users asking the same question: Out of the two or more CPUs I'm considering, which one is the best? The specific CPUs in question vary, but the fundamental problem remains the same. However, the answers these users receive, despite being shared with good intentions, frequently lead to more confusion rather than clarity. On one hand, you might encounter someone like myself, attempting to convey that comparing CPUs isn't as straightforward as determining which one is simply the best or better. On the other hand, some individuals might advocate for a particular CPU as the best option based on a specific use-case, potentially ignoring the CPUs originally mentioned in the query.
So, to help prospective PC Builders avoid annoying tech nerds like me, I aim to create a comprehensive guide on how to independently compare CPUs. Once you've read this guide, you'll hopefully never have to deal with me again.
We'll explore the various specifications that you need to consider when choosing a CPU, like cores, threads, clock speed, and more. We will also discuss the interaction between CPUs and other PC components. Finally, we'll put theory into practice by comparing some CPUs.
Understanding CPU Specifications
Cores and Threads, How Many Do I Really Want or Need?
When you first start comparing CPUs, you will be bombarded with technical specifications. It will feel overwhelming at first, but we can cut-out some noise and learn to focus on a few key points in order to simplify our decision-making process.
One of the first specifications we'll hear a lot about in CPU performance discussions is core and thread count. Multiple cores were not always desired for PC Builders who were focused on gaming performance. This is because, historically, games were largely single-threaded, meaning they were primarily designed to run on a single core. This limitation was due to both the programming complexities of multi-threaded applications and the hardware available at the time.
However, as technology advanced, this scenario started changing. The advent of dual-core and then quad-core processors marked the beginning of a new era. Developers began designing games to take advantage of multiple cores, creating multi-threaded applications that could split their workload across cores. This change was slow at first, as adapting to this new paradigm was no easy task for game developers. Still, as multi-core processors became increasingly prevalent, more games started to take advantage of this architecture.
Fast forward to today, games and game engines have become far more sophisticated and capable of leveraging multiple cores and threads. Contemporary AAA games, known for their high-fidelity graphics and complex mechanics, often require quad-core CPUs as a minimum specification, with many benefiting from six or even eight cores.
Additionally, CPU technologies like Hyper-Threading (Intel) and Simultaneous Multithreading (SMT from AMD) have gained prominence. These technologies allow a single CPU core to handle two instruction streams or threads simultaneously, essentially allowing them to do more work within the same time frame. While not all games can effectively utilize these additional threads, those that do, especially some modern titles with high CPU requirements, can see substantial performance benefits.
That said, it's important to remember that, like all things in technology, the more is better rule doesn't always apply. Other factors, such as the game's specific requirements, the CPU's architecture, its clock speed, and how it interacts with the rest of your system (such as the GPU), all play vital roles in determining gaming performance.
Do You Have a Need? A Need for Clock Speed?
Clock speed, measured in gigahertz (GHz), signifies the number of cycles a CPU can execute in one second. When CPUs were single-core, clock speed was the primary measure of how fast a CPU could run a game. The higher the clock speed, the more instructions it could execute per second, and consequently, the smoother the game would run. During this bygone period, each new generation of CPUs focused on increasing clock speed as a means of boosting performance.
However, the importance of clock speed started to evolve as CPUs became more complex. With the advent of multi-core processors, manufacturers began to focus on increasing the number of cores, which led to a period where clock speed increases became less pronounced.
Fast-forward to the present day, where most modern games are designed to utilize multiple cores and threads, and you might wonder if clock speed has lost its relevance. The answer is: not quite. Clock speed still plays a significant role in gaming, although it's now considered in conjunction with other factors like core count and thread count.
Even in multi-threaded games, there are often certain operations that are primarily handled by a single core. One such operation is the main game loop, sometimes also referred to as the rendering thread. This loop handles various critical tasks like processing player inputs, updating game physics, and executing AI behavior. Due to their sequential nature and dependency on previous results, these tasks can't be easily divided among multiple cores. For these operations, the single-core performance, which is heavily influenced by the core's clock speed, can be critical.
Furthermore, not all games are optimally programmed for multi-threading. Especially some older and indie games may not fully utilize multiple cores, making a high clock speed particularly beneficial for these titles.
Understanding CPU Boosting
CPU boosting, also known as turbo boost for Intel processors and turbo core for AMD processors, is a feature that allows a CPU to automatically increase its clock speed above its base speed when the demand arises and thermal conditions allow. This temporary acceleration in speed can significantly enhance the performance of the CPU, enabling faster data processing when handling demanding tasks like gaming or rendering videos.
It's important to note that the boost speed is not a permanent state. It operates within the CPU's power, current, and temperature specifications to ensure the longevity of the processor. For instance, if a CPU's temperature goes beyond the safe limit, the boost feature will be disabled to prevent overheating.
When comparing CPUs, the base and boost clock speeds can give you a sense of the CPU's overall performance potential. However, it's also essential to consider how effectively the CPU manages heat and power consumption during these high-performance periods. Some CPUs might offer a high boost speed but struggle to maintain that speed for extended periods due to thermal throttling. This is particularly relevant for tasks that require sustained high performance, like gaming or 3D rendering. Therefore, it's crucial to consider both the raw numbers and how effectively the CPU can manage and sustain its boost speeds.
Let's Cache In
When comparing CPUs, one important but often overlooked factor is the CPU cache. CPU cache is a small amount of high-speed memory located on the CPU die that stores frequently accessed data and instructions. By doing this, the CPU can avoid time-consuming trips to the slower main system RAM, thus improving performance.
Here's a brief overview of CPU cache and why it matters in gaming:
Types of Cache: CPUs typically have three levels of cache - L1, L2, and L3. L1 cache is the smallest and fastest, but it's also the most expensive to manufacture, so there's not much of it. L2 and L3 caches are larger and slower, but they're also less expensive and therefore more abundant. A CPU uses all three levels in a hierarchical fashion, first checking the L1 cache for data, then the L2, and finally the L3.
Impact on Gaming Performance: CPU cache can have a significant impact on gaming performance. Games are complex programs that require the frequent accessing of a variety of data and instructions. The quicker a CPU can access this data, the faster it can render frames, leading to higher frame rates and smoother gameplay. A CPU with a larger cache can store more of this frequently accessed data close at hand, which can lead to better gaming performance.
Generational Gaps
Over the years, CPU design has undergone significant changes, which can lead to confusion when deciding which CPU to buy. It can be challenging to determine whether to opt for the latest and most powerful CPU line from Intel or AMD, or to save money by selecting an older model that appears quite similar on the surface.
Each new move to the next generation of CPU used to represent a significant leap forward in performance thanks to Moore's Law. First articulated by Gordon Moore, co-founder of Intel, in 1965, predicted that the number of transistors on an integrated circuit (or CPU) would double approximately every two years. This once facilitated the creation of smaller, faster, and cheaper electronic devices. However, Moore's Law wasn't so much a law of physics as it was a self-fulfilling prophecy: a target that the tech industry aimed for and mostly succeeded in achieving.
In recent years, it's become apparent that Moore's Law has faltered. The reasons are primarily physical and economic:
Physical Limits: As transistors become smaller, we're reaching a point where the laws of physics start to pose serious challenges. Transistors can't be shrunk indefinitely; they're already approaching the size of individual atoms. At this scale, quantum effects that can disrupt their operation become significant.
Economic Factors: The cost of designing and building the fabrication plants required to create these ever-smaller chips has skyrocketed. So while it may still be technically possible to continue to shrink transistors, it's becoming less economically viable to do so.
What does this mean when comparing CPU performance between generations? Well it now means that we no longer see a straight-forward increase in clock speed and core count, as we once did in the past. Instead we see more subtle changes in CPU architecture and design that is seeking more clever ways to increase performance. These designs do not always show up in a spec sheet, and in particular will not appear in the same places we once looked to.
So let's go into what differences you may still see in new CPU generations, if not a doubling of transistors:
Architecture and Design: The primary driver of performance improvements in modern CPUs is often enhancements in architecture and design. Each generation brings refinements that make CPUs more efficient and capable, such as better ways of scheduling and executing instructions or enhanced cache designs. These changes can impact how quickly a CPU processes instructions, how much power it uses, and how much heat it generates.
Efficiency and Clock Speed: While large leaps in clock speed are less common in modern CPU generations, improvements in efficiency continue. These changes mean that newer CPUs can often do more with the same or even less power than their predecessors, which can lead to performance enhancements and reduced heat production.
New Features and Technologies: Modern CPU generations often introduce new features and support for the latest technologies. These can range from support for new instruction sets that can enhance performance in certain tasks to improvements to integrated graphics. These updates can lead to better compatibility with newer software and hardware, and in some cases, noticeable performance improvements in specific tasks or games. One of the biggest features to look for right now is PCIe 5.0 support. The latest CPUs support PCIe 5.0, which offers double the bandwidth of its predecessor, PCIe 4.0. This is particularly beneficial for high-speed components like NVMe SSDs and the latest generation of graphics cards.
Do I Want Integrated Graphics?
Integrated graphics refers to a GPU that's built directly into a CPU. Not all CPUs come with integrated graphics. Integrated graphics have some unique advantages and considerations, both for those planning to use them alone and those intending to pair them with a discrete GPU.
Integrated graphics can be a valuable feature for those on a tight budget, or for those whose computing tasks don't require the power of a dedicated GPU. They are quite capable of handling basic tasks like web browsing, office applications, and streaming video. They can even manage some light gaming, especially on older or less graphically demanding titles.
Another advantage is that having integrated graphics can be a lifesaver if your discrete GPU fails. Instead of being left without any display output, you can fall back on your integrated graphics until you replace or fix your GPU.
If you're planning to install a discrete graphics card, you might wonder if there's any benefit to having integrated graphics. There can be.
Modern systems allow you to dedicate your integrated graphics to specific tasks, freeing up resources on your discrete GPU. This can sometimes lead to better overall performance. For example, you could use your integrated graphics for a secondary monitor or for less intensive tasks, leaving your discrete GPU free to focus on gaming or heavy rendering.
However, if you're planning on using a discrete GPU, you should consider saving money by choosing a CPU without integrated graphics. Integrated graphics, while bundled into the CPU architecture, is not free.
Interactions and Compatibility with the Motherboard and other Components
Sockets and Chipsets
To truly grasp the significance of your CPU choice, it's crucial to understand how the CPU interacts with other components in your PC. When selecting a CPU, not only are you choosing the brain of your system, but you're also defining the ecosystem in which your computer will operate.
The CPU is placed in a socket on the motherboard, forming the core of your system. The type of socket on your motherboard dictates which CPUs you can use. Additionally, the combination of your CPU and motherboard will determine what chipset will be used. The chipset serves as the communication center and traffic controller for the motherboard, influencing how information is managed between the CPU and other hardware components. Different chipsets can offer varying features and performance levels, so you'll want to research the latest available chipsets for the CPUs you are targeting, and find a motherboard that supports it.
Buses and PCIe Lanes
The CPU communicates with different parts of your PC through 'buses'. These data highways allow information to travel between components. Buses vary in speed and bandwidth, with faster buses enabling smoother and quicker data transfer.
The PCIe bus in your system will be of particular importance if you plan on building with discrete graphics or NVMe SSDs (solid state drives). Each CPU supports a certain number of PCIe lanes, which are used to connect high-speed components like graphics cards and NVMe SSDs directly to the CPU. The more lanes a CPU supports, the more components it can connect with simultaneously, allowing for potential upgrades and scalability in your PC build. In order for you to fully utilize the high transfer speeds of a high-end GPU or NVMe drive, you'll need to ensure you have enough high-speed lanes supported by your CPU.
Comparing CPUs
Comparing Specs
Let's now summarize what we learned about CPU specifications, and apply it how we can compare the specs of two different CPUs:
Cores and Threads: Look at the number of cores and threads. More cores allow for better multitasking and improved performance in applications designed to take advantage of multi-core processors. Threads, particularly in CPUs with Hyper-Threading or Simultaneous Multi-Threading, can also boost performance in multi-threaded tasks. However, buying a CPU with a high core-count that still has high clock speeds will get expensive. For gaming on a budget it can be smart to stay in the range of 4-8 cores.
Clock Speed: Clock speed, measured in gigahertz (GHz), indicates the speed at which the CPU can execute instructions. A higher clock speed typically translates to faster performance, though this also depends on other factors like IPC (Instructions Per Cycle).
Cache Size: Larger cache sizes can help improve performance by reducing the time it takes for the CPU to access frequently used data.
TDP (Thermal Design Power): TDP indicates the maximum amount of heat a system or chip can produce that the accompanying cooling system is designed to deal with under workload. This can affect both the CPU's performance and the type of cooling system you'll need. If you're considering a CPU with a high TDP, you'll need to ensure your current or planned cooling system, be it an air cooler or a liquid cooler, is capable of adequately dissipating that heat. This is particularly important if you're building a small form factor PC, where heat dissipation and power efficiency are major considerations.
Remember, while these specifications are important, they don't tell the whole story. Different architectures and technologies can make a big difference in real-world performance.
Compatibility
When comparing CPUs, it's crucial to consider compatibility with the other components of your PC:
Motherboard: Ensure that the CPU is compatible with your motherboard, both in terms of the CPU socket and the chipset. Check the motherboard's support list to confirm.
RAM: CPUs can also have limitations on the type and speed of RAM they support.
Cooling System: Make sure your cooling system is sufficient for your CPU's TDP.
Power Supply: Ensure your power supply can handle the power requirements of the new CPU, along with your other components.
Additional Research
Finally, it's always a good idea to read CPU reviews and benchmarks. They provide real-world performance data and can help you understand how a CPU performs in tasks similar to what you'll be doing. Keep in mind, though, that these should serve as a general guide and not the definitive decision-maker for your CPU purchase. Your specific needs and circumstances should always drive your decision.
Case Study: Comparing Two CPUs
To bring these concepts to life, let's conduct a case study comparing two hypothetical CPUs: the AMD Ryzen 7 5800X and the Intel Core i7-10700K. We'll evaluate their specifications, performance, and compatibility to understand how the factors we've discussed affect their real-world performance.
Specifications
Starting with the specifications, the Ryzen 7 5800X has 8 cores and 16 threads with a base clock speed of 3.8 GHz, capable of boosting up to 4.7 GHz. It has a TDP of 105 watts, a total cache of 36 MB, and supports PCIe 4.0.
On the other hand, the Core i7-10700K also has 8 cores and 16 threads, but its base clock speed is slightly lower at 3.8 GHz, though it can boost up to 5.1 GHz. It has a higher TDP of 125 watts, a total cache of 16 MB, and supports PCIe 3.0.
SpecificationAMD Ryzen 7 5800XIntel Core i7-10700KCores88Threads1616Base Clock Speed3.8 GHz3.8 GHzBoost Clock Speed4.7 GHz5.1 GHzTDP105 Watts125 WattsTotal Cache36 MB16 MBPCIe VersionPCIe 4.0PCIe 3.0SocketAM4LGA 1200
Considering their clock speeds, both CPUs are capable of delivering solid performance. However, differences start to emerge when we consider other factors.
For instance, the Ryzen 7 5800X's support for PCIe 4.0 could make it a more suitable if you're considering using newer, high-speed components that take advantage of PCIe 4.0's increased bandwidth, such as your GPU or NVMe drive.
On the other hand, the Core i7-10700K's higher boost clock speed may give it a slight edge in tasks that benefit from high single-core speed. However, its higher TDP means it might run hotter and require a more robust cooling solution, potentially increasing the total cost of ownership.
Additionally, you would need to ensure the rest of your system is compatible with these CPUs. The Ryzen 7 5800X uses the AM4 socket, while the Core i7-10700K uses the LGA 1200 socket, so you would need a motherboard with the correct socket for each. The choice of motherboard could also influence the availability of features like PCIe 4.0 or support for faster RAM speeds.
Conclusion
This guide has taken us through the crucial elements of CPUs, from their basic components to the nuances involved in comparing specifications. We've explored cores, threads, clock speed, cache, and the significance of CPU generations. Also, we've touched on the importance of considering factors like TDP, integrated graphics, and how the CPU interacts with other components.
Remember, the CPU is the versatile workhorse in your computer. Its value isn't just in its raw specifications, but also in how those specs translate to real-world performance for your specific needs and how well it meshes with the rest of your PC build.
Choosing a CPU goes beyond just picking the most powerful or the newest; it's about finding the best fit for your needs and your budget. This understanding equips you to make an informed decision when building your PC.
Share Your Thoughts
What are your thoughts on this guide about picking a CPU? Do you have any experiences you'd like to share? Your insights can be a great help to others who are contemplating a similar decision.
Additionally, I'm always looking for new topics to cover in my blog. If you have a question about custom PC builds, or if there's a specific topic you'd like me to delve into, please let me know in the comments section below via my contact form. Your question could be the inspiration for our next blog post!