Computer Processor (CPU) Buying Guide – What to Know
A computer processor, also known as the CPU (Central Processing Unit), is the brain of a computer; it’s what does the “thinking”. The computer processor knows a small number of primitive instructions (ie. add, subtract, move data) and these basic instructions, executed at lightning speeds, do everything a computer can do. When shopping for a CPU, unless you have a very specific type of computation you are looking for, the general rule of thumb to keep in mind is, you get what you pay for.
The cost of a processor usually reflects its performance. While AMD processors can offer cheaper cost/core, Intel processors offer faster high end processors for extreme performance. AMD processors usually do not exceed mid-range performance, so if you think you will require a high performance computer in the future, you will want to go with an Intel processor.
Intel or AMD?
Unless you are building a super computer, you can choose either Intel or AMD similar-priced mid-range processor without seeing much of a difference in performance. However, the processor that you choose will determine which motherboard you will buy. When switching from Intel to AMD (or vice versa), the computer parts that need to be replaced are the processor and the motherboard. You can remove your Intel motherboard and CPU, replace it with an AMD motherboard and CPU, and your computer will continue to work. Keep in mind that you cannot simply replace the processor and switch from Intel to AMD or vice versa.
The CPU socket provides a connection between your CPU and the motherboard. The computer processor sits in the CPU Socket slot on the motherboard and can be easily replaced without the need to solder. As new processors come out, the architecture changes, requiring the structure of the motherboard sockets to change accordingly. If you will want to replace your CPU in the future, you will have to either purchase a faster CPU of the same socket type, or upgrade your motherboard if you want to purchase a processor with a newer socket type.
Some popular socket types for Intel are LGA 1151, LGA 2011, LGA 1150, and LGA 1155. If you are looking for an Intel processor, you will most likely want one of those.
- The LGA 1151 is the latest socket design from Intel that accepts the new Skylake class of 14nm processors, supporting the 6th generation Core processors in the 6000 series. If you are looking for the latest socket type design that will support many processors in the years to come, this is what you need.
- Intel’s LGA 2011 socket was released after the 1155. It was designed to support 6-core processors and is generally used for extreme high end systems. If money is a concern, you want to refrain from purchasing this socket type, as you do not get the best bang for your buck with this one.
- Socket LGA 1150 supports the 4th generation Intel Core processors, as well as some of the 5th generation processors. This socket type is popular, although has its upgrade limitations.
- The LGA 1155 is one of the older socket types, supporting the 2nd generation Intel Core processors, as well as Ivy Bridge 3rd generation processors. Though older, they are significantly cheaper, and still provide decent performance. Refrain from purchasing this socket type if you need a long term processor.
Popular socket types for AMD are, newest to oldest, Socket FM2+, Socket FM2, Socket AM3+, and Socket AM3.
- AMD’s Socket FM2+ is the latest socket type introduced in 2014, compatible with AMD Accelerated Processing Units (APUs) such as “Richland” and “Trinity”. This is the recommended socket type for AMD.
- Socket FM2, predecessor of the FM2+ socket, was release in 2012 and designed for the Trinity series of the APUs. An older yet still popular socket type.
- Socket AM3+ was released in 2011 and supports a wide range of AMD processors such as the FX Vishera, FX Zambezi, Phenom II, Athol II, and Sempron. Socket AM3+ was designed for the new Bulldozer processors and supports all previous generation AM3 processors.
- Socket AM3 was released in 2009 in order to support integrated DDR3 memory controllers such as Phenom II. This is one of the older socket types and we discourage purchasing this one if you want a long lasting CPU.
Number of Cores
A CPU core can be thought of as an independent processor within a physical CPU. These cores execute programs independently from each other, which substantially increases the performance of your computer. So if your computer has 4 cores, you can run up to 4 programs simultaneously. If you run more than 4 programs, cores begin to “juggle” more than 1 program, and share the resources of a core. If you only run 1 program or game in a 4 core system, does it execute it on all 4 cores, then? That depends on the program and how it was designed. A core executes a string of instructions from any given program called a thread. These “threads” is what the cores are juggling. If a program or a game supports multi-threading, you can take advantage of your extra cores to increase performance. If you run a single-threaded program or game, you will not see performance boost merely by increasing the number of cores. The program you are running must be taking advantage of the extra cores to benefit from them.
The clock speed determines how quickly a processor can execute instructions from a process. The motherboard pulses electricity through the processor at a specific frequency, for example, 3.2GHz, which means that every second, the motherboard pulses electricity through the processor 3.2 billion times. You might be thinking, does that mean that the higher the processor frequency the faster the processor will be? Not exactly. Certain instructions a processor executes may take multiple pulses to perform. Various processors take different number of pulses to execute different primitive commands. Also, every core in the processor executes every pulse. So a 3.2GHz hexa-core processor executes 3x faster (at 19.2GHz) than the same frequency dual-core processor (at 6.4GHz). The clock speed is just one of the indicators of the CPU speed, but far from being the only indicator. It might be tempting, but refrain from buying a CPU purely based on the clock speed.
Many processors on the market now support integrated graphics. That means that, if the motherboard supports it, you don’t need to buy a video card separately, and instead have your processor do the video processing. Normally, a processor that does not support integrated graphics, will require that you buy a discrete video card. If you plan on doing gaming, photoshop, video editing, or any other video-intensive activities, you should still purchase a separate video card as they are much faster at processing video than CPUs are.
The new Turbo Boost technology by Intel and Turbo Core technology by AMD allows a processor, if sufficiently cooled and powered, to temporarily increase its clock speed to provide extra performance. Unlike overclocking, this is done completely automatically, without your need to worry about. Needless to say, the amount of Turbo Boost a processor can attain reflects the increase in the price of the processor. For example, the 3.3GHz Core i7-3960X Extreme Edition is able to Turbo Boost to a frequency of 3.9GHz without the need to overclock. You have no control over this feature, but it’s good to know what your processor is capable of.
64 Bit Support
Nearly every processor on the market today is 64 bit, with majority of applications designed for 64 bit processors. That is to say, a processor can read/write more data per clock cycle as opposed to previous generations of CPUs. This provides a significant boost to performance, as well as allowing much more RAM/Video Memory to be installed. 32 bit processors are obsolete at this point, and should be avoided.
Caching is a means of temporarily storing important data for quick access. Memory data that the processor access often will be stored in the cache, so that the next time it needs to access it, it checks the cache first. The advantage of caching is, although accessing RAM is extremely fast, processor cache is much, much faster, and gives your computer a huge speed boost. More cache, however, is also more expensive. Processors usually have 3 caches Level 1(L1), Level 2 (L2), and Level 3 (L3).
Level 1 cache is the processor’s fastest and primary core-level cache, which has the most impact on the processor’s performance. It’s responsible for storing data and instructions that the processor is working with.
Level 2 cache is larger, slower, and functions just like Level 1 cache, except for L2 cache feeds instructions to L1.
Level 3 cache is larger than L2 cache, but slower (due to sharing across all cores), and feeds instructions to L2 cache.
As a rule of thumb, the more memory you have in all 3 caches, the faster your processor will perform, although the performance gain is logarithmic.
Thermal Design Power
Thermal Design Power (TDP) rating indicates how much power a processor will consume at full load. If you have a 1000W power supply, for instance, you do not need to worry about this. However, if you have a 400W power supply, combined with a high end video card, you might not have enough to power all of your components, including the CPU. LGA 1155 sockets consume 35 to 95 watts of power, whereas LGA2011 socket consumes 130, therefore the LGA2011 TDP is 130. Keep in mind, when purchasing a processor, that the motherboard is able to handle your processor’s TDP. An inadequate motherboard could burn or even catch fire if you are able to run the CPU at full load, so that is worth noting.
Overclocking is modifying your motherboard’s frequency to force the processor to operate faster beyond its standards. Overclocking may be risky as it puts a huge stress on your computer’s components, and even cause permanent damage if not done correctly. This topic is beyond the scope of this article, but in general, it is not recommended to overclock your computer – just buy a faster processor.