Comparison Apple iMac 21.5" 2015 MK142 vs Apple iMac 21.5" 2013 ME087

The general type (specialization) of the processor installed in the PC.

— Desktop. Processors originally designed for full-sized desktop computers. The specific characteristics of such CPUs can vary quite widely; however, in general, they have higher processing power than mobile chips, as well as a wider range of additional features and special solutions to improve efficiency. And with the same actual performance, desktop solutions are much cheaper than mobile ones. The downside of these advantages is the relatively high energy consumption and heat dissipation. However, for full-sized PCs, these shortcomings are not critical, so almost all traditional desktop computers, as well as most all-in-ones (see "Type") are equipped with this particular type of processor; and for powerful gaming models, a desktop CPU is mandatory by definition. On the other hand, this category also includes rather economical and "cold" low-power chips, which are suitable for compact computers that do not require high performance, such as nettops and thin clients.

— Mobile. This term in this case refers to processors originally designed for laptops. Most of these CPUs use the same basic architecture as desktop models — x86. Their main differences are: on the one hand, reduced energy consumption, reduced clock frequencies and low heat generation, on the other hand, less computing power in general. However the actu...al characteristics of such processors may vary from model to model, some laptop solutions are not inferior to fairly advanced desktop ones; however, with similar capabilities, a laptop processor will cost significantly more. Thus, this type of CPU is mainly used in nettops and individual models of monoblocks (see "Type"), where it is difficult to use powerful cooling systems.
A rarer variety of mobile processors used in modern PCs are chips based on the basic ARM architecture. Such processors have even lower heat dissipation and power, and are also often implemented in the System-On-Chip format, when the CPU itself, RAM, wired and wireless connection controllers, and other components are combined in one chip. ARM solutions can be found in Android touchscreen all-in-ones (which are effectively "desktop tablets"), as well as in individual thin clients.

The specific model of the processor installed in the PC, or rather, its index within its series (see "Processor"). The full model name consists of the series name and this index — for example, Intel Core i3 3220; knowing this name, you can find detailed information about the processor (characteristics, reviews, etc.) and determine how suitable it is for your purposes.

The number of cores in a complete PC processor.

The core is a part of the processor designed to process one stream of commands (and sometimes more, for such cases, see "Number of threads"). Accordingly, the presence of several cores allows the processor to work simultaneously with several such threads, which has a positive effect on performance. However note that a larger number of cores does not always mean higher computing power — a lot depends on how the interaction between command streams is organized, what special technologies are implemented in the processor, etc. So, only chips of the same purpose (desktop, mobile) and similar series (see "Processor") can be compared by the number of cores.

In general, single-core processors are practically not found in modern PCs. Mainly desktop chips of the initial and middle level are made dual-core. Four cores are found both in desktop CPUs of the middle and advanced class, and in mobile solutions. And six-core and eight-core processors are typical for high-performance desktop processors used in workstations and gaming systems.

Clock speed of the CPU installed in the PC.

In theory, higher clock speeds have a positive effect on performance because they allow the CPU to perform more operations per unit of time. However, this indicator is rather weakly related to real productivity. The fact is that the actual capabilities of the CPU strongly depend on a number of other factors - the overall architecture, cache size, number of cores, support for special instructions, etc. As a result, you can compare by this indicator only chips from the same or similar series (see “CPU”), and ideally, also from the same generation. And that's pretty approximate.

Processor clock speed when running in TurboBoost or TurboCore mode.

Turbo Boost technology is used in Intel processors, Turbo Core — AMD. The essence of this technology is the same both there and there: if some of the cores work under high load, and some are idle, then some tasks are transferred from more loaded cores to less loaded ones, which improves performance. This usually increases the clock frequency of the processor; this value is indicated in this paragraph. See above for more information on clock speed in general.

The amount of cache memory level 2 (L2) in the complete PC processor.

The cache is an intermediate memory buffer into which the most frequently used data from the "RAM" is written during the operation of the processor. This has a positive effect on system performance. The larger the cache, the more data can be stored in it for quick access and the higher the performance (ceteris paribus). As for the level, the higher it is, the larger and slower the cache. Thus, the L2 cache occupies an intermediate position between the small and fast L1 cache and the large but relatively slow L3 cache. The minimum size of this buffer in modern PC processors is 512 KB, in most models this figure does not exceed 8 MB, however, there are chips with an L2 cache of 16 MB or even more.

The amount of cache memory level 3 (L3) in the complete PC processor.

The cache is an intermediate memory buffer into which, when the processor is running, the most frequently used data from the "RAM" is written. This has a positive effect on system performance. The larger the cache, the more data can be stored in it for quick access and the higher the performance (ceteris paribus). As for the level, the higher it is, the larger and slower the cache. The third cache level is the highest, respectively, the most voluminous and the slowest. Its minimum volume in modern PCs is about 2 MB, and the most advanced processors can have 20 – 30 MB of L3 cache.

The clock speed of the RAM that comes with the PC. This is one of the parameters that determine the capabilities of RAM: with the same amount and type of memory (see above), a higher clock frequency will mean faster performance. However such details are rarely required by an ordinary user, but they are important for enthusiasts and professionals.

Also note that this indicator can be used to determine the possibilities for upgrading the system: the motherboard will be able to work normally with brackets that have the same or lower clock frequency, but compatibility with faster memory should be specified separately.

The number of slots for RAM modules provided on the PC motherboard. In this case, we are talking about slots for removable strips; for a PC with built-in memory, this parameter is irrelevant.

The slots available on the "motherboard" can be occupied all, partially or not occupied at all (in models without RAM). Anyway, you should pay attention to their number if the initially installed amount of RAM does not suit you (or ceases to suit you over time), and you plan to upgrade the system. The smallest amount found in a PC with removable memory is 1 slot ; if it is busy, you will only have to change the bar when upgrading. More connectors for RAM are always paired, this is due to a number of technical nuances; most often this number is 2 or 4, but it can be large — up to 16 in powerful workstations.

Note that when planning an upgrade, you need to take into account not only the number of slots and type of memory (see above), but also the characteristics of the motherboard. All modern "motherboards" have restrictions on the maximum amount of RAM; as a result, for example, the presence of two DDR4 slots does not mean that two strips of maximum capacity can be installed in the system at once, 128 GB each.