An ATX motherboard will fit in an EATX case with the help of standoffs, if not effortlessly. EATX is just an extended version of ATX with similar mounting screws and a slightly different port selection.
But Intel released EATX, ensuring backward compatibility with ATX. So, they have two rows of screws in common, using which you can fit an ATX mobo inside an EATX case.
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Are EATX and ATX the Same
EATX and ATX are not the same, although they share quite a bit of similarity. They have a lot in common but differ in size, port selection, and heat dissipation.
1. Form Factor
Size is the main differentiating factor between EATX and ATX motherboards. The rest of the differences originate from this one key area of separation.
a) Is EATX Bigger Than ATX
EATX boards have a larger footprint compared to their ATX counterparts. As for dimensions, ATX boards measure 12 inches × 9.5 inches (305mm × 244mm), whereas the EATX ones are 12 inches × 13 inches (305mm × 330.2mm).
So, there’s a difference due to the few extra inches on the right side of the EATX boards. And you will need one of those full towers to house them. That also explains why EATX boards get seen mostly in servers where space isn’t a problem.
On the other hand, ATX motherboards will fit into your regular mid-tower case without any issues. Their smaller form factor, however, comes at the cost of slightly worse heat dissipation overall. Not to mention how cramped they may feel working with sometimes.
2. Ports and Sockets
Other than the obvious size difference, EATX and ATX motherboards differ in terms of port selection.
A modern-day ATX mobo comes with 2-3 PCI-e 4×16 expansion slots as opposed to four or more on its EATX counterpart. So, you have easy access to using GPUs in parallel when working with an EATX motherboard, a feature ATX boards lack.
As per today’s standards, ATX boards have evolved to house as many as eight SATA ports. Yet, they are still no match for EATX boards and the amount of room they have for SATA I/O.
c) RAM Slots
Generally, ATX motherboards will have a maximum of four RAM slots, whereas EATX ones can feature up to eight DIMM (dual in-line memory module) slots. That, in turn, can provide support for extending memory up to 256GB, a definite overkill for most PCs. But having such an option is something you can brag about.
d) I/O Ports
Since EATX motherboards usually get featured in servers, they have way more I/Os than ATXs. As a result, you get the freedom to connect more peripherals to them. Besides, most EATXs come equipped with faster ethernet ports and better network cards.
e) CPU Sockets
Most interestingly, some EATX mobos can even come with more than one CPU socket, allowing for double the power. Although it may sound like overkill, servers can benefit from such parallel computing capabilities.
As you might already know, having multiple CPUs inside an ATX is not an option, no matter the price you pay.
Overview of ‘Will ATX Case Fit In EATX Case’
Despite having a different form factor, ATX motherboards will fit in EATX cases. That is because EATX got released as an extended version of ATX, with backward compatibility for housing smaller boards. As a part, you will find an option to use standoffs in most, if not all, EATX cases.
However, if one of the manufacturers (board or case maker) doesn’t maintain the industry standards, you might be out of luck. But again, that is too rare of an event.
Typically, EATX cases come with three rows of screw holes. In ideal conditions, the first two rows will align with the screws on the ATX boards. Or at least the backplate will perfectly line up even if the screw holes don’t.
And if the screw holes don’t match, you can still use your ATX inside an EATX case. But in that case, make sure you have enough standoffs for the motherboard to be mounted properly. Regardless of the manufacturer, there will be square holes on the motherboard tray where the standoffs will go in.
Can MATX Fit In EATX Case
MATX boards have mounting points that are a subset of those on a regular ATX. Besides, they have an I/O panel identical to their bigger brother, meaning they are backward compatible. So, your everyday mid-tower ATX cases can house a micro ATX without an issue.
And since EATX cases can be home to ATX mobos, it can house the smaller MATX also. However, such a setup will require quite a handful of standoffs.
Although ATX motherboards can fit in EATX cases, they may look slightly off, given the left-out space. Nevertheless, EATX cases, being larger, have better air circulation and good heat dissipation, therefore. So, there will be less trouble related to heating issues.