This time I would like to give you some new information about PC motherboards, and this time I will focus on another important thing to take care of when we need a new mobo: its size aka form factor. The quantity of features a motherboard offers is also influenced by how spacious it is, and this has also something to do with which kind of computer case you choose or already have at home. So this is going to be a motherboard size guide explaining also the connection between cases and mobos.
Motherboards must match case sizes
Maybe you just want to replace the motherboard and keep your existing PC case, PSU, fans, cooling system & other stuff… however, in the case of cases and motherboards there are some size factors that are tightly related to each other, and you have to keep in mind these size standards as you may buy, say, a motherboard that’s too large and does not fit into the case, or even if the case has enough space inside, maybe it just does not support the size of your new motherboard, meaning that you cannot mount it / tighten its screws to the motherboard if the screw holes don’t match.
That is, motherboards and cases share some common form factor standards, and you surely wouldn’t just want to simply put the motherboard on a table (or on the floor!) without having a case for your PC, although it is still possible to connect other hardware pieces to the mobo and then even power it up and down while it lies outside a case – it would be an uncommon PC design (at most: suitable for hardware tests like those on YouTube), and then leaving the motherboard outside would make it more vulnerable – you may happen to spill water or coffee on it, or your pets might climb on that table and get onto the mobo. Not to mention that if it sits on the floor, someone may accidentally walk there! When there’s a case, things look differently.
Fortunately, there are some precisely defined standards for motherboard sizes, and most cases usually support several types of sizes, meaning there are some “concentric” sets of screw holes, designed to match each mobo size, from narrowest to widest. When you buy a new motherboard, it surely comes with its own set of screws (by experience, when I bought new cases, they did NOT have screws by themselves, only the motherboards were provided with those).
But well, I think the situation may differ from a piece to another. Be sure that you will get screws when purchasing the motherboard, and if your current case supports its size (you should keep the manual of the case, and remember what those size types are), then you won’t have to spend extra money for a new case as well.
An entire scale of Mini sizes!
You may have already seen that some motherboards look smaller and others are more spacious, also featuring plenty of SATA ports, large CPU sockets, five or even more PCI-E slots… Personal computers are, after all, an entire world themselves, and there are differences as between us! And our tastes & preference sets are different too. When we say “the best computer for me” or “the best pieces I need for my PC”, some may mean the most affordable (which can also be among the cheapest or taking less space), others may think of a medium-ranged configuration, and enthusiasts are targeting high-tech systems whose dimensions are impressive too. Computer technology has already taken care of this variety of preferences and thus we have a set of form factor standards. Remember that cases and motherboards are interconnected when it comes about supported mobo sizes!
We will start the size exposure with the tiniest motherboards on the market. And I promised to give you real examples too. So let’s go!
1) The Mobile ITX format is rated as the smallest one for motherboards. VIA Technologies introduced it in the 2000s. Previously, the ITX (it stands for Information Technology eXtended) had been launched in November 2001, and we will see which ITX standard was chronologically the first one. Now back to Mobile ITX, its motherboards are pretty tiny: 6 cm * 6 cm (2.4” * 2.4”)! Can you imagine that fitting into an open hand? It is so small that it has no computer I/O ports. You would have to use it in conjunction with a carrier board (or base board) which at its turn features a Computer-On module.
These modules are also small form-factored, and intended for use with embedded products (like, I guess, that Mobile ITX board). This module would provide the Operating System, the device drivers and some Board Support Packages (BSPs). The Mobile ITX board type is… mobile, of course, and it’s used for military, medical and transportation embedded markets. It may be integrated into phones too! Around 2010, there was released the EPIA-1700 Mobile-ITX board.
2) The Pico ITX format was also announced in 2007 and subsequently released by VIA technologies, Inc. Its dimensions are not much greater than the Mobile’s ones: 7.2 cm * 10 cm (2.8 ” * 3.9 ”). This time, we get CPU and RAM support on them. Supported CPUs vary from Pentium N4200 up to 7th-gen Intel Core i7 processors, and depending on model, the memory can be up to 1 GB DDR2-400 or 533, or even a slot of 16 GB of DDR4-2133. The board supports AGP add-on video cards too, but well, that’s already a pretty old standard. Some model names: PICO318, PICO319, PICO50R, PICO51R. On more advanced Pico ITX boards we may find also USB 2.0/3.0 paired ports, and also SATA600 & M.2 support, in single-slot configurations (M.2 expansion cards may be included).
So if you want a very small motherboard (for a Box computer) and still benefit from some hardware power, Pico ITX would be an option!
3) The Nano ITX format was proposed by VIA in 2003. It measures 12*12 cm (4.7 ” * 4.7 ”), and by example we can find them in car computers, due to their low-profile design.Some model names are NANO840 and NANO842. They support Celeron or Atom Processors (at least as far as I have seen on them), up to 8 GB of DDR3L-1066 or 1333 memory, one single SATA-300 port, Mini PCI cards, video support like DVI/HDMI… and of course they have a very low power consumption. But obviously their supported features are somewhat older than in the Pico case.
4) The Mini ITX format was, in fact, the first form factor ITX came up with, when VIA released ITX in November 2001. We are already starting to be able to get more modern tech features by getting to this motherboard type. It measures 17*17 cm (6.7 * 6.7 inches), it can be used in small PC configuration systems, and another good point is that their four screw holes align well with four of the larger ATX motherboard format (to wchch we’ll get later…), so you can mount a Mini ITX in a larger case! Their manufacturers include Intel, AMD, Arm, Transmeta, PowerPC.
This time, the ranges of supported CPUs and RAM becomes pretty large, and you can use 8th-Gen Intel Core CPUs, even some high-end LGA2066 CPUs – by example, AsRock launched the X299E-ITX/ac board, you can put the 10-core i9-7900X CPU on it, six SATA-III ports, up to 128 GB of DDR4 memory (four slots though, you will have to find 4*32GB modules). And three M.2 slots. So you can have good benefits from a pretty small mobo like this Mini ITX one!
Other Mini ITX models belong to chipsets like Z370, Z390, B450-I (like the AMD-socketed MSI B450I Gaming Plus, supporting 3rd-gen Ryzen CPUs and up to 32 GB DDR4 memory).
Let’s move to a larger scale!
Having finished talking about the smallest motherboards, let’s now move upwards to a larger configuration specification that applies to motherboards, cases and even supported power supplies. Yes, sometimes the dimension of the case affects also our possibility to mount a PSU in there, PSUs require their own mounting space (their placement may vary, it can be in the upper or lower zone of the case, i.e. above or below the motherboard if the case is a Tower) and cases have to support them. So we must actually pay attention to the whole trio case-motherboard-power supply!
As for PSUs and ITX PC motherboards, you can use an ATX power supply for powering an ITX mobo up too, the connectors match. But your case has to be large enough for the PSU to fit well in. I said that Mini ITX mobos can be mounted in larger cases (like the ATX ones). And there the ATX PSUs are welcome as well.
So, now it is about the ATX standard. This specification is older than the previous ITX one, Intel developed it in 1995 for improving the previous AT standards (do you remember the old AT computers?). We are very familiar with this format, many of us have ATX-based configurations at home (motherboards, power supplies, cases – do not forget the trio above). There is a very large number of products that match this family of form factors. We will see the ATX-based motherboard formats one-by-one, starting from the lowest one. So we have:
1) The FlexATX format was released by Intel in 1999. Its motherboards measure 229*191 mm (or 9*7.5 inch), so its dimensions are several centimeters above the MiniITX. There can be at most three expansion slots (like old PCI slots, or modern PCI-E ones as well). From what I see, this format is preferred on servers and the models are pretty expensive (several thousand dollars a mobo). Since FlexATX is compatible with other ATX formats like MicroATX and ATX itself (we’ll get there soon), these motherboards fit well into ATX-supporting cases.
Although I am supposed to be focusing on personal computers rather than on servers, these server boards – the modern way, like the SuperMicro X11SDV-16C-TP8F – support Intel Xeon CPUs, we may see 12 SATA3 ports (yes, that pile of ports, it’s on the Server side after all), several M.2 slots, up to 256 GB of RAM support (once again, that’s Server, the DDR4-2400 memory is of type Registered ECC RDIMM, and there may even be up to 512 GB of LRDIMM… but let’s not dive into Server details that much, though). The bottom line is that FlexATX boards are quite powerful ones, and also not intended for regular PCs. When it comes to PCs, this FlexATX format is an extraterrestrial one!
2) The microATX format (also mATX) came out in December 1997. It measures 24.4 cm * 24.4 cm (9.6*9.6 inch), and it’s worth to say that the FlexATX above was developed as a reduced form of mATX. mATX fits well into ATX-rated cases too, since also its mounting set (screws, screws…) is a subset of the classical ATX one. Its motherboards support AMD, Intel, and VIA CPUs, and have at most four PCI or PCI-Express slots. For Gaming users who want their computers to take a little less space in the house, there is a lot on mATX dedicated motherboards, and there also exist small mATX cases!
Again from my personal experience, the oldest computer in my home has a MicroTower case, and the motherboard model is Acer Veriton M490G (released 2010), which is exactly a microATX board! It was pretty good at its time, and it’s still helpful to me now, e.g. for using the Internet at home. It supports an Intel Core i5-650 CPU, six SATA2 ports… but wait, this is 2019, there are already much modern mATX boards on the market. Just to say I know how it is like to have a mATX-based computer, too. The PSU is a 300W FSP Group model, and it stands in the upper part of the case.
As of nowadays’ mATXes, there are wonders like MPG Z390M GAMING EDGE AC, that supports 9th-gen Intel Core i9 CPUs (yes, i9-9900K too), and 128GB of DDR4 memory up to 4500 MHz (Overclocking). It features four SATA3 ports and two M.2 slots. There are also two PCI-E 3.0 x16 (longest ones) slots, and two of x1 (shortest possible ones).
Another mATX motherboard is ASRock X570M Pro 4, which supports 3rd AMD Ryzen CPU s and has three PCI-E 4.0 slots, besides eight SATA3 ports and two M.2 slots. You can also use 128 GB of DDR4 on it, if you mount four 32 GB modules.
And the EVGA X299 mATX version 2 supports even 18-core, 36-threaded processors like i9-10980XE, 64 GB of DDR4 RAM, six SATA3 ports, as well as having M.2 and U.2 support. Its “version 1” counterpart had only one 8-pin CPU power connector, which was making it less likely to cope with the power of a 18-core CPU.
So, by getting to the microATX step you can already have a vrey strong equipment & save space at home!
3) Here comes the Mini ATX format definition. There are two variants, one of them is actually smaller than microATX. So, by Mini ATX we can mean a 15*15 cm (5.9*5.9 inch) size that was developed by AOpen, Inc. Or Intel’s definition that measures 28.4 * 20.8 cm (11.2 * 8.2 inch), which originally fitted in the ATX definition, being later removed after Micro ATX came out. Although Intel’s old Mini ATX definition is still listed on Wikipedia, to me it results that the only available type remained the 15*15 cm one, that can be used in car computers or tower cases.
The Gigabyte GA-F2A78M-HD2 board seemed to match a MiniATX definition, however on their site it’s listed as a 22.6*17.4 cm Micro ATX, and it looks pretty old, supporting the AMD FM2+ socket (Athlons included), and up to 64 GB of DDR3 RAM, as well as four SATA-III internal connectors. But as for its dimensions, it really doesn’t match exactly any of the standards above.
For the moment I am unable to find a concrete example of Mini ATX board, so let’s move forward.
4) The ATX format itself, maybe the most worldwide-spreaded motherboard size, measures 30.5 * 24.4 cm or 12 * 9.6 inches. There is really plenty of ATX motherboards, PSUs and cases around us. I have myself three such ATX-based computers at home, their motherboards are: MSI X299 SLI PLUS, ASUS PRIME X299-A, GIGABYTE X299 AORUS GAMING 9. Some of these have support for 36-threaded CPUs like Intel Core i9-7980XE, of course support up to 128 GBs of DDR4 memory (eight slots of memory this time, not only four like in small-sized models), feature up to 8 SATA-III ports (whereas smaller models had room for at most six), have up to three M.2 slots, maybe even U.2 support (the SLI PLUS one), they have up to five PCI-E slots too… and an ATX board like the AsRock X399 Taichi can theorically support even the 32-core, 64-thread AMD Ryzen Threadripper 2990WX that was released last year.
Now it’s time to know that some cases offer us support for even larger motherboards, and that the most gifted PC mobos are often greater than ATX, in order to have enough room for their tons of features. So, if you want a motherboard that is “best of the best” in matters of storage space, many slots, huge CPUs (and AMD Threadrippers have big sockets, that’s known: theirs is bigger), then most probably you will need an extra-large board that has to fit into a huge case as well! So let’s see some large sizes too.
5) The eATX format aka extended ATX, that is featured by an enough number of high-end desktop PC motherboards (obviously they cannot fit into laptops…), actually comes in about five flavors whose common part is the length: 30.5 cm or 12 inch, same as in the classic ATX, but their width varies by model, like the standard eATX size that is 30.5 * 33 cm (12*13 in), but there are also some narrower formats – width is smaller, like 257 mm, 264 mm, 267 mm, 272 mm (respectively 10.1, 10.4, 10.5, 10.7 in). Speaking for myself, I also have two eATX motherboards at home: the MSI X299 XPOWER GAMING AC (30.5 * 27.2 cm) and the MSI X399 MEG CREATION (rated as 30.4 * 27.2 cm on the MicroStar International site).
eATX desktop motherboards have certain benefits from their extra space over the regular ATX pieces: by example, my XPOWER GAMING AC has 10 SATA-III ports (eight native, two provided by an AsMedia controller), as well as an U.2 slot. The MEG Creation doesn’t have more than 8 SATA ports, but it was well designed to cope with the 32-core 2990WX behemoth, having 16+3 power phases. Other extremely gifted eATX motherboards have up to seven PCI-E ports (like the ASUS WS X299 SAGE that supports i9-7980XE CPUs).
You should carefully check the shops for finding suitable cases, like large Tower ones, in order to be able to support eATX boards, especially those that are wider than 30 cm. The bottom part of the case must ensure enough space for the PSU to be mounted in safety, and the right part (the one with storage racks) must also have some centimeters of free space between the margin of the motherboard and the rack zone. You also need enough space for coupling the SATA cables to the board in that zone, without much stress and without being forced to excessively bend them because of not having enough room. So make sure your case is spacious enough, even for regular ATX boards, and especially for those larger!
And now, let’s start an “extraterrestrial” motherboard size tour!
6) The XL-ATX format is really designed for extreme Desktop PC configurations, and from now on, you really, really must put your attention on finding an extremely large case, too. This format also came in three distinct flavors, like 343 * 262 mm (13.5*10.3 in) from EVGA, 345*262 mm (13.58*10.31 in) from Gigabyte, 345*264 mm (13.6*10.4 in) from MicroStar International aka MSI. Also, some motherboards called as XL-ATX may have slightly different dimensions when having the specs exposed on their sites, like 32.5 * 27.5 cm for the Gigabyte TRX40 AORUS XTREME, that should soon support the newer Ryzen 3970X 32-core Threadripper CPU. And a treasure like the Gigabyte AORUS X299X Extreme Waterforce that must support the Intel Core i9-10980XE CPU, besides having an excellent watercooling monoblock.
In January 2020 we should look amazed at the powers of the new 64-core, 128-thread 3990X Threadripper, and I am sure there will be some XL-ATX motherboards being able to deal with this juggernaut too.
And let’s leave the newest boards alone for a little, for diving a bit into the past: around the 2011-2012 winter there was launched an Intel X79 Express motherboard that was called Big-Bang XPower II. It also belonged to the XL-ATX family (345*264 mm), matching exactly the MSI size pattern since MSI manufactured this board.
At its time (it received BIOS updates until 2014), this motherboard supported Intel Core i7 processors of the 2011 socket (meaning there were 2011 pins on the motherboard CPU socket), 128 GB of DDR3 memory up to 2400 MHz via overclocking, four PCI-E 3.0 slots of the “x16” length (which however does NOT mean that all of them had the capacity to run at 16-lane bandwidth), other three PCI-E 2.0 slots (yes, this board was mixing PCI-E generations), two SATA-III ports via the specific Intel® X79 chipset, four extra SATA3 ports via the ASMedia® ASM 1061 chipset, and… four more SATA-II ports via the same Intel X79 chipset. So this board justified its extra space by lots of SATA ports and PCI-E slots, while it also mixed SATA2 and SATA2 generations, as well as PCI-E 2 & PCI-E 3!
So, a motherboard may have different PCI-E and SATA generations on it, and there is also backwards compatibility (PCI-E 3.0 cards can work with PCI-E 2 slots, this applies to SATA3 ports vs SATA2 too, and also PCI-E 4.0 slots may accept PCI-E 3.0 cards. However, this backwards & different-gen thing does NOT apply everywhere. You cannot mix DDR3 and DDR4 memories on board, and neither plug the wrong generation module into the DIMM slot!
Let’s also name an example of a PC case that would be good for several kinds of motherboards, in terms of size: the be quiet! Dark Base Pro 900 offers support for five formats: XL-ATX, eATX, ATX, microATX, and Mini-ITX.
Also,Corsair 1000D is a case that supports SSI EEB, eATX, ATX, mATX, and Mini-ITX.
If things go fine, I will also be able to post affiliate links for directing you to the good products. By now, you have also two case names that would be helpful with hosting the majority of the desktop motherboards!
As far as I know, when it comes to laptop motherboards, things are different and they have proprietary form factors. So my article suits very well the Desktop PC area. In future posts, I will be covering also laptops and Mac PC devices. And even later, perhaps servers too. Speaking of which, let’s see some interesting stuff below.
Some Server-Desktop mix
By now, I have exposed the main PC-oriented motherboard sizes. There are also some more form factors, like the server-oriented Enhanced Extended ATX or EE-ATX (347*330 mm or 13.68*13 in), developed by SuperMicro, SSI EEB / CEB / MEB / TEB (where SSI stands for Server System Infrastructure, while the “EBs” are “Electronics Bay”, being either Enterprise or Compact / Midrange / Thin), whose dimensions are respectively 305*330 mm (12*13 in) for EEB, 305*267 mm (12*10.5 in) for CEB, 411*330 mm (16.2*13 in) for MEB, 305*267 mm (12*10.5 in) for TEB, and also other standards like Intel’s discontinued BTX and WTX, AMD’s Mini-DTX, and Supermicro’s SWTX that is for quad processors and is not ATX-compatible.
As for the EEB standard, although it’s more for servers, it is still worthy of mentioning that the ASUS ROG Dominus Extreme motherboard, with 35.5*35.5 cm (14*14 in), was designed to host Intel’s biggest Desktop CPU (by now), the Xeon W-3175X (compatible with the Intel C621 server chipset) with 28 cores and 56 threads, that also supports 192 GB of DDR4 RAM on 12 DIMM slots (placed 6+6, on the left and right side of the CPU socket that has 3647 pins). In spite of the C621 chipset being server-dedicated, that Xeon processor is considered a “Desktop” Xeon. However, new Desktop Threadrippers should have the crown :).
We have a quite overwhelming variety of sizes in computers world, just like when looking for shoes or clothes :). Motherboards, that are the flesh of our computers (while cases are the skins), have to be looked for while we have a well-established criteria list for choosing them: besides specific features, sizes matter too.
And normally, just like flesh is covered by skin, motherboards must stay in their cases, that are required to provide enough internal space so that our mobos can stay safe in there. And sometimes great features don’t necessarily mean big sizes too, just like in the human life.
Though we also noticed that more features and powers tend to unavoidably mean larger space (XL-ATX, SSI EEB).
Whatever we choose, the “skin size” has to match the “flesh size”.
And if you found this information interesting, feel free to comment on it! Sharing is also open.