CPU Explained: How to Select the Best Processor(10 terms)

By asas / September 25, 2021

Processors

One of the most important things that decide the power of your gadget is its CPU. From Intel’s 4004 -the first microprocessor which performed 60,000 OPS (operations per second), addressed 640 bytes of memory, to processors which do trillions of calculations per second was a great journey. OEMs flaunt the processor used in their new device, Manufacturers say how efficient their chip is. But what exactly are cores, threads, clock speed, etc? what should we bother while choosing a processor? Let’s find out.

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What exactly a Processor Is?

We know that processors are the ‘brain’ of our computers and mobile phones. But what exactly is a processor and how does it work? what makes it different from a GPU. A processor is a silicon die that is engraved with millions of tiny circuits of different types, which includes cache, io controller, device controller, CU, AU, etc. It may contain multiple cores and multiple threads which all work in synchronization with a clock’s tick. Finding out about a processor’s real-world performance from specs may be inaccurate, but they can be very helpful. so in this post, let’s discuss what are the 10 things we should look out for when choosing a processor, laptop, or mobile.

This is a beginner-friendly post. checkout this post by free code camp for more technical details

1.Cores

A core is a single processing unit in a processor, that can do tasks on its own. Each core will have its own primary cache, registers, etc. In other words, cores are virtually different processors in a single socket that can process data independently. Having multiple processors in a single device is a very bad idea, because of all the extra hardware, cooling, etc needed to make that, also two different physical processors are very difficult to be synchronized which may lead to data losses, process failures, etc. cores solve this problem by acting as multiple virtual processors inside a single die, which share many common resources, thereby also reducing the overall cost while increasing the performance.

Those who just use your phone or PC for casual browsing, word editing, etc, might not benefit from having many cores, but if you do highly parallel tasks(tasks that can be cut and done independently of each other) such as video editing, 3D rendering, machine learning, data manipulation, AAA games, etc, having more than 4 cores might really be important. But for other general use, a regular 4 core CPU might be enough. But stay away from 2 core CPUs because even windows are not comfortable using 2 cores.

2. Threads

Multithreading or threads are used inside the cores to increase the performance with a minimum increase In cost and power consumption. Threads are different from cores as cores are a full set of hardware with the ability to do processors, which are independent of other cores, while threads are like multiple pathways for instructions to go to a single processing unit without the delay for fetching the data. Unlike cores, they share a large amount of hardware together and hence are cost-efficient and less power-hungry.

Why not just use more cores instead of multi-threading?

Having more cores in a physical CPU requires each individual core to be smaller, and are also costly considering the fact that each individual core requires its own registers, primary cache, etc. a thread on the other hand share many of these vital and expensive components so is much less expensive. at the same time, it can give up to 1.7x performance increase depending on the process.

3.Cache

Caches are extremely fast volatile memory inside the CPU die itself. It is used as temporary storage between Ram and the processing unit. There are 3 levels of cache, when a process is being done, the data to be processed is stored in ram from the hard drive, then to the cache from ram for faster access by the processor. The more cache, the faster the processor can access data and hence the faster it becomes. Whatever the use may be, more cache results in better performance.

• L1 cache – fastest , inside the core , upto 32KB.
• L2 cache -faster ,inside cluster , upto 4MB.
• L3 cache -fast , insidee the die , upto 32MB

4.Clockspeed

It is the number of times a processor executes instructions. It is usually in the range of Gigahertz (10⁹) instructions per second. Meaning that every second the processor executes this many times. There are multiple cores, other devices, etc. all these are synchronized by an internal clock. The clock frequency is the number of times it clicks. As the general rule of thumb, having higher clocks delivers more performance.

Advertised clock speed: Speed claimed by the manufacturer in optimal conditions.

Boot clock: Under ideal conditions, processors can clock over the advertised voltage for a little time for a small burst of performance, this higher clock is called a boost clock.

Underclocking: When the CPU is idle, the processor automatically slows down to a lower clock speed to save energy and reduce heating.(many also set their base clock to a lesser value ) this clock is called underclocking.

5.Transistor size

As we all know, processors work using billions of transistors that act as nanoscopic switches, that turn on and off to process and manipulate data. The size of the transistor has a profound impact on all the other metrics. For example, when the size of individual transistors is reduced, more transistors can be packed inside a single die, they can be clocked higher with the same heat output. etc. We came to form about 600nm to as low as 5nm, obeying Moore’s law, and it is very hard to reduce the transistor size further, 3nm is our last hope, and after that, we would need to find new technologies.

Always prefer lower transistor size as it improves power efficiency, higher performance, etc.

6.TDP

TDP stands for Thermal Design Power and is used to measure the amount of heat a processor(or graphics cards, and other electronic components) is expected to output when under load. For example, a CPU may have a TDP of 90W, and therefore is expected to output 90W of heat when in use. The ideal type depends on cooling capabilities, ultrabooks generally use a 15W CPU where gaming laptops use as much as 55W and desktop processors way above that. But always ensure proper cooling for higher TDP devices or else the CPU will be under volt.

7.Integrated GPU

This is probably the most misinterpreted term while choosing a laptop. Most people think their laptop has a dedicated graphics card when actually it is an integrated GPU or GPU. the vega graphics of ryzen processors, UHD graphics of intel processors, and the new iris Xe of 11th gen intel processors, Adreno of snapdragon, and Mail are all examples of integrated GPU. They are not as powerful or feature-rich as discrete GPUs but on the other hand, provide substantial performance increase in graphics tasks for budget laptops, computers, and ultrabooks, where an option of a dedicated graphics card is not much valid. Even though casual games on low-medium settings can be played with these processors.

Always priorities an Nvidia 1650 or above, Radeon RX 5500M, or above-dedicated graphics cards if your main intent is gaming/video editing/3d rendering, etc. There is a line of discrete graphics cards dedicated to ultrabooks by Nvidia, the MX series. (MX250,350,430,450) etc. Even though they are dedicated graphics cards, they do not have substantial performance increase in games, neither bring hardware accelerators like their GTX ad RTX siblings. So only consider them if you are buying a laptop with Intel UHD graphics.

8.IPC

IPC or instructions per cycle/clock, tells how many things a CPU can do in a single cycle. While clock speed is the cycles complete in a second, IPC is the number of tasks a CPU can conduct in each cycle. So the effective performance of a single core is the product of its clock speed and IPC. So a CPU having a lower cock but higher IPC might still beat a processor with faster clock speeds.

Note that a CPU’s IPC can vary based upon the workload. So the  CPU manufacturers usually don’t share IPC information in spec sheets.

9.Bench marks

As we saw, there are several variables that determine the effective performance of a processor and even after that, the CPU might just end up underperforming than advertised. this is where we use benchmarks. there are many benchmarks such as geekbench, Antutu, PCMark, etc which tests the CPU on a predefined load, while measuring many matrics, and outputs a score based on the result. different benchmarks prioritize different scenarios, for example, cinebench is almost entirely dependent on multicore performance while compression test checks compression so consider multiple results before finalizing.

For mobile phones check Antutu or Geekbench, For Pc, check cinebench, geekbench, PCMark, etc to get a rough idea of what to expect from the chip.

10.Architecture

This is a very deep and technical topic, but for this post, we shall only discuss the basics. Architecture is the way a processor (graphics cards etc.) is designed. The most popular ones are the X86 (used in computers, by Intel, AMD, etc) and Arm (used by Qualcomm, Apple, Samsung, MediaTek, etc). Historically the difference has been simple. Arm chips were less powerful, but very energy efficient at the same time, perfectly fitting in most appliances, watches, smartphones, etc. and X86 were the powerful used in computers, laptops, servers, etc.

But Due to the rapid development in the mobile industry, arm has come a long way in just over a decade, and now is finding their way into laptops, desktops, and even servers. Still, the PC market is being dominated by X86 CPUs. unless you are buying a MacBook, go for an X86 Cpu in PCs and arm is the only option when it comes to mobiles.

Bottom line:

There is no clear winner or best processor to choose from. Everything depends on what is going to be your use and budget. But while comparing similar products, this list might help you a lot. If you have any doubt or need assistance choosing a laptop, phone, or any other product, contact me on WhatsApp.

Hope you like this post. Comment if I am missing something or done any mistakes. Read my other posts below.