Comparison Apple iMac 21.5" 4K 2019 MRT42 vs Apple iMac 27" 5K 2015 MK472

Diagonal of the screen installed in a monoblock (see "Type").

In general, the larger the diagonal, the more advanced both the screen and the computer as a whole are considered. The large display size is convenient for games, movies, and some special tasks like layout of large printed materials; in addition, a higher resolution can be provided for such a screen, and more space is available inside the case for advanced components. On the other hand, a larger monoblock will cost much more than a relatively small one, even if the other characteristics of such models are completely the same. In addition, the power of the hardware is not directly related to the size of the screen — high-end monoblocks can be quite small.

As for specific numbers, a diagonal of 20" or less is considered very limited nowadays, monoblocks of 21.5" are small, a 24" screen is medium, and values of 27" and 32" indicate large sizes.

Resolution of the screen installed in the monoblock (see "Type").

The higher the resolution, the clearer and more detailed image the screen can produce, but the more expensive it is. In addition, high resolutions require corresponding powerful graphics, which further affects the price of the entire computer. The minimum indicator for modern monoblocks is actually 1366x768 — this resolution allows, in particular, to play HD 720p video in proper quality. However, nowadays, the more advanced format is most widely used — Full HD, providing a resolution of 1920x1080. And in high-end monoblocks with a large diagonal and powerful graphics, there are also more solid resolutions — Quad HD(2560x1440, 3440x1440), Ultra HD 4K(3840x2160, 4096x2304) and even 5K(5120x2880) standards.

The maximum brightness provided by the monoblock screen (see "Type").

The more intense the ambient light, the higher the screen brightness should be for normal visibility. The most "dim" screens in monoblocks are capable of delivering up to 200 cd / m2 — this is more than enough to work under ordinary artificial lighting, but under sunlight it will take at least 300 cd / m2. At the same time, modern monoblocks can also have a larger margin of brightness — in some models up to 500 cd / m2. This expands the possibilities for customizing the screen for different situations and user preferences. In addition, high brightness has a positive effect on image quality and colour saturation, in light of which it is often a sign of a fairly advanced screen.

Monoblock native screen contrast (see "Type"). This indicator describes the ratio between the brightest white and the darkest black that the screen is capable of displaying. And the higher this ratio, the higher the quality of the picture, the more reliable the colour reproduction and the better the details in the lightest and darkest areas of the image are visible.

It is worth noting that the real contrast even in professional matrices almost never exceeds 5000:1, however, much higher figures can be given in the characteristics — at the level of 100000000:1 (one hundred million to one), even in relatively inexpensive screens. This means that the manufacturer went to the trick and indicated in the characteristics not static (real), but the so-called dynamic contrast. It describes the difference between the brightest white at maximum brightness and the darkest at minimum; it is unrealistic to achieve such indicators within one frame, so this is more advertising than practically significant information. At the same time, we note that there are "smart" backlight technologies that allow you to change its brightness in certain areas of the screen and achieve a higher contrast in one frame than the claimed static one; these technologies can be used in premium devices.

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.

The number of threads supported by the bundled PC processor.

A thread in this case is a sequence of instructions executed by the kernel. Initially, each individual core is able to work with only one such sequence. However, among modern CPUs, more and more often there are models in which the number of threads is twice the number of cores. This means that the processor uses multi-threading technology, and each core works with two instruction sequences: when pauses occur in one thread, the core switches to another, and vice versa. This allows you to significantly increase performance without increasing the clock frequency and heat dissipation, however, such CPUs are also more expensive than single-threaded counterparts.

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.