Comparison Asus PRIME B660-PLUS D4 vs Asus PRIME B660M-A D4

The form factor of the motherboard determines, first of all, its physical dimensions, and, accordingly, a number of parameters directly related to them: type of computer case, installation method, type of power connector, number of slots for additional boards (expansion slots), etc. At the moment, there are such main form factors of motherboards:

— ATX. One of the most common form factors for PC motherboards. The standard size of such a board is 30.5x24.4 cm, it has up to 7 expansion slots and a 24-pin or (less often, in older models) 20-pin power connector.

— Micro-ATX. A slightly reduced version of the ATX form factor, with more compact dimensions (usually 24.4x24.4 cm) and, accordingly, fewer places for peripherals — there are usually only two slots for "RAM", expansion slots — from two to four. Nevertheless, despite the limited size, such boards can be intended for quite powerful systems.

— Mini-ITX. Motherboards of compact dimensions (17x17 cm). Designed for use primarily in small form factor computers (small form factor, SFF), in other words, compact PCs. According to the mounting specifications and the location of connectors and slots, they are compatible with ATX standard cases. They usually have one expansion slot.

— mini-STX. Another representative of compact form factors, assuming a boar...d size of 140x147 mm. Thus, the overall size is almost a third smaller than mini-ITX. At the same time, such motherboards often have seats for fairly powerful processors (for example, the LGA 1151 socket for Intel Core chips) and are made based on the corresponding TDP values. But expansion slots, usually, are absent.

— micro DTX. A relatively new compact form factor, which is not common, mainly among rather specific motherboards — in particular, models designed for cases in the PIO form factor. This form factor is characterized by a very small size and weight and allows you to mount the case directly behind the monitor, on a standard VESA mount. One of the features of "motherboards" for such systems is that the graphics card is installed along the board, and not perpendicularly — accordingly, the PCI-E 16x connector (see below) has a non-standard location. At the same time, micro-DTX boards are similar in terms of fasteners to microATX and can be used in cases of the corresponding form factor (except that additional equipment may be required for the correct installation of a graphics card). The standard size of such a board is 170 x 170 mm, similar to mini-ITX.

— mini DTX. An intermediate format between the microDTX described above and the original DTX; sometimes also described as an extended mini-ITX version. It has a standard size of 170 x 203 mm and can be equipped with two expansion slots (mini-ITX and mini-DTX have one such slot); it is completely similar in application — it is intended mainly for compact cases, in particular, HTPC computers.

— XL-ATX. Larger version of the ATX form factor. While not yet a common standard, size options include 32.5x24.4cm with 8 expansion slots and 34.3x26.2cm with up to 9 expansion slots.

— Thin mini-ITX. A “thin” version of the reduced mini-ITX form factor described above: according to the official specification, the total thickness of the thin mini-ITX board should not exceed 25 mm. Also designed for the most miniature computers — in particular, HTPC.

— E-ATX. The letter E in the name of this form factor stands for "Extended" — extended. True to its name, E-ATX is another enlarged version of ATX using 30.5x33cm boards.

— EEB. Full name SSI EEB. The form factor used in server systems (see “By direction”) provides a board size of 30.5x33 cm.

— CEB. The full name is SSI CEB. Another form factor of "server" motherboards. In fact, it is a narrower version of the EEB described above, with a width reduced to 25.9 cm (with the same height of 30.5 cm).

— flex-ATX. One of the compact variations of ATX, which provides board dimensions of less than 229x191 mm, as well as less than 3 expansion slots. At the same time, in terms of the location of the mounting holes, this standard is identical to microATX; in fact, it was developed as a potential replacement for the latter, but for a number of reasons it did not receive much distribution, although it continues to be produced.

— Non-standard (Custom). The name Proprietary is also used. Motherboards that do not conform to standard form factors and are designed for cases of special sizes (usually branded ones).

Motherboard dimensions in height and width. It is assumed that the traditional placement of motherboards is vertical, so in this case one of the dimensions is called not the length, but the height.

Motherboard sizes are largely determined by their form factors (see above), however, the size of a particular motherboard may differ slightly from the standard adopted for this form factor. In addition, it is usually easier to clarify the dimensions according to the characteristics of a particular motherboard than to look for or remember general information on the form factor. Therefore, size data can be given even for models that fully comply with the standard.

The third dimension — thickness — is considered less important for a number of reasons, so it is often omitted.

The maximum RAM clock speed supported by the motherboard. The actual clock frequency of the installed RAM modules should not exceed this indicator — otherwise, malfunctions are possible, and the capabilities of the “RAM” cannot be used to the fullest.

For modern PCs, a RAM frequency of 1500 – 2000 MHz or less is considered very low, 2000 – 2500 MHz is modest, 2500 – 3000 MHz is average, 3000 – 3500 MHz is above average, and the most advanced boards can support frequencies of 3500 – 4000 MHz and even more than 4000 MHz.

The number of M.2 connectors provided in the design of the motherboard. There are motherboards for 1 M.2 connector, for 2 connectors, for 3 connectors or more.

The M.2 connector is designed to connect advanced internal devices in a miniature form factor — in particular, high-speed SSD drives, as well as expansion cards like Wi-Fi and Bluetooth modules. However, connectors designed to connect only peripherals (Key E) are not included in this number. Nowadays, this is one of the most modern and advanced ways to connect components. But note that different interfaces can be implemented through this connector — SATA or PCI-E, and not necessarily both at once. See "M.2 interface" for details; here we note that SATA has a low speed and is used mainly for low-cost drives, while PCI-E is used for advanced solid-state modules and is also suitable for other types of internal peripherals.

Accordingly, the number of M.2 is the number of components of this format that can be simultaneously connected to the motherboard. At the same time, many modern boards, especially mid-range and top-end ones, are equipped with two or more M.2 connectors, and moreover, with PCI-E support.

Electrical (logical) interfaces implemented through physical M.2 connectors on the motherboard.

See above for more details on such connectors. Here we note that they can work with two types of interfaces:

• SATA is a standard originally created for hard drives. M.2 usually supports the newest version, SATA 3; however, even it is noticeably inferior to PCI-E in terms of speed (600 MB / s) and functionality (only drives);
• PCI-E is the most common modern interface for connecting internal peripherals (otherwise NVMe). Suitable for both expansion cards (such as wireless adapters) and drives, while PCI-E speeds allow you to fully realize the potential of modern SSDs. The maximum communication speed depends on the version of this interface and on the number of lines. In modern M.2 connectors, you can find PCI-E versions 3.0 and 4.0, with speeds of about 1 GB / s and 2 GB / s per lane, respectively; and the number of lanes can be 1, 2 or 4 (PCI-E 1x, 2x and 4x respectively)

Specifically, the M.2 interface in the characteristics of motherboards is indicated by the number of connectors themselves and by the type of interfaces provided for in each of them. For example, the entry "3xSATA / PCI-E 4x" means three connectors that can work both in SATA format and in PCI-E 4x format; and the designation "1xSATA / PCI-E 4x, 1xPCI-E 2x" means two connectors, one of which works as SATA or PCI-E 4x, and the second — only as PCI-E 2x.

Number of PCI-E (PCI-Express) 1x slots installed on the motherboard. There are motherboards for 1 PCI-E 1x slot, 2 PCI-E 1x slots, 3 PCI-E 1x ports and even more.

The PCI Express bus is used to connect various expansion cards — network and sound cards, video adapters, TV tuners and even SSD drives. The number in the name indicates the number of PCI-E lines (data transfer channels) supported by this slot; the more lines, the higher the throughput. Accordingly, PCI-E 1x is the basic, slowest version of this interface. The data transfer rate for such slots depends on the PCI-E version (see "PCI Express Support"): in particular, it is slightly less than 1 GB / s for version 3.0 and slightly less than 2 GB / s for 4.0.

Separately, we note that the general rule for PCI-E is as follows: the board must be connected to a slot with the same or more lines. Thus, only single-lane boards will be guaranteed to be compatible with PCI-E 1x.

Number of PCI-E (PCI-Express) 16x slots installed on the motherboard.

The PCI Express bus is used to connect various expansion cards — network and sound cards, video adapters, TV tuners and even SSD drives. The number in the name indicates the number of PCI-E lines (data transfer channels) supported by this slot; the more lines, the higher the throughput. 16 lanes is the largest number found in modern PCI Express slots and cards (more is technically possible, but the connectors would be too bulky). Accordingly, these slots are the fastest: they have a data transfer rate of 16 GB / s for PCI-E 3.0 and 32 GB / s for version 4.0 (for more information about the versions, see "PCI Express Support").

Separately, we note that it is PCI-E 16x that is considered the optimal connector for connecting video cards. However, when choosing a motherboard with several such slots, it is worth considering the PCI-E modes supported by it (see below). In addition, we recall that the PCI Express interface allows you to connect boards with a smaller number of lines to connectors with numerous lines. Thus, PCI-E 16x will fit any PCI Express card.

It is also worth mentioning that in the design of modern "motherboards" there are slots of increased sizes — in particular, PCI-E 4x, corresponding in size to PCI-E 16x. However, the type of PCI-E slots in our catalog is indicated by the actual throughput; so only connectors that support 16x speed are considered as PCI-E 16x.

Operating modes of PCI-E 16x slots supported by the motherboard.

For more information about this interface, see above, and information about the modes is indicated if there are several PCI-E 16x slots on the board. This data specifies at what speed these slots can operate when expansion cards are connected to them at the same time, how many lines each of them can use. The fact is that the total number of PCI-Express lanes on any motherboard is limited, and they are usually not enough for the simultaneous operation of all 16-channel slots at full capacity. Accordingly, when working simultaneously, the speed inevitably has to be limited: for example, recording 16x / 4x / 4x means that the motherboard has three 16-channel slots, but if three video cards are connected to them at once, then the second and third slots will be able to give speed only to PCI-E 4x level. Accordingly, for a different number of slots and the number of digits will be appropriate. There are also boards with several modes — for example, 16x/0x/4 and 8x/8x/4x (0x means that the slot becomes inoperable altogether).

You have to pay attention to this parameter mainly when installing several video cards at the same time: in some cases (for example, when using SLI technology), for correct operation of video adapters, they must be connected to slots at the same speed.

The number of USB 2.0 connectors provided on the motherboard.

USB connectors (all versions) are used to connect to the "motherboard" USB ports located on the front panel of the case. With a special cable, such a port is connected to the connector, while one connector, usually, works with only one port. In other words, the number of connectors on the motherboard corresponds to the maximum number of front USB connectors that can be used with it.

Specifically, USB 2.0 is the oldest version widely used nowadays. It provides data transfer rates up to 480 Mbps, is considered obsolete and is gradually being replaced by more advanced standards, primarily USB 3.2 gen1 (formerly USB 3.0). Nevertheless, a lot of peripherals are still being produced under the USB 2.0 connector: the capabilities of this interface are quite enough for most devices that do not require a high connection speed.