Difference between eATX versus mATX?

[leveller]

Hey,

I will be building a PC with an mATX motherboard and I was wondering what restrictions I might face. I’ve never owned an mATX motherboard before (always used eATX) and what do I lose exactly with an mATX board?

I'm not interested in overclocking and tweaking at all. But what I do want is to be able to use a top spec CPU (currently a Ryzen AM4 5950X, but soon to be AM5 9000X3D series) and GPU (4090, but will swap out for the 5090 later).

assuming my PSU is powerful enough will I hit hurdles or problems using a small form factor mATX board?

The Lian Li A3 mATX case I have already bought is a great small case with plenty of cooling solutions for adding the AIO CPU and AIO GPU so heat shouldn’t be a problem and quietness will be achieved.

[Tetras]

Less expansion slots (M.2, PCIE) and sometimes RAM slots (2 instead of 4), but it depends on the motherboard.

[Agall]

8 minutes ago, leveller said:

Hey,

I will be building a PC with an mATX motherboard and I was wondering what restrictions I might face. I’ve never owned an mATX motherboard before (always used eATX) and what do I lose exactly with an mATX board?

I'm not interested in overclocking and tweaking at all. But what I do want is to be able to use a top spec CPU (currently a Ryzen AM4 5950X, but soon to be AM5 9000X3D series) and GPU (4090, but will swap out for the 5090 later).

assuming my PSU is powerful enough will I hit hurdles or problems using a small form factor mATX board?

The Lian Li A3 mATX case I have already bought is a great small case with plenty of cooling solutions for adding the AIO CPU and AIO GPU so heat shouldn’t be a problem and quietness will be achieved.

eATX has no standard width to the board, but uses ATX length standards.

mATX has a standard of 9.6" by 9.6" in width and length.

 

Regarding what you lose with mATX, not much if you're only using a dGPU for expansion. The argument against mATX would be future PCIe expansion, which with a large dGPU like an RTX 4090, you're maybe getting the last PCIe slot. That mostly doesn't matter now except for a 1x slot or so for an upgraded WLAN/NIC or aux hardware, a lot of which is perfectly obtainable with USB instead.

 

The significant downside to mATX is that's usually the budget category, so finding premium mATX boards is difficult. Asus sometimes puts out interesting mATX boards, the most interesting I owned was their x79 HEDT mATX board that I ran SLI 780Ti's in. There is an X670e AM5 mATX board that Asus put out that's quite feature rich, but that's not common and they're unlikely to make an X870e version (its also price gouged or out of stock circa a year ago).

 

Personally, I've recommend for a while and just finally got one in hand to build a system in, the best mATX case is the Asus AP201. Its also regularly between $55-$75 USD. It falls into that perfect ratio of size that can house the most extreme hardware, as long as its with a mITX or mATX motherboard. Top mounted 360mm AIO compatibility or a giant air cooler and plenty of room for the biggest of GPUs with full sized PSU support.

[podkall]

47 minutes ago, Agall said:

eATX has no standard width to the board, but uses ATX length standards.

mATX has a standard of 9.6" by 9.6" in width and length.

 

Regarding what you lose with mATX, not much if you're only using a dGPU for expansion. The argument against mATX would be future PCIe expansion, which with a large dGPU like an RTX 4090, you're maybe getting the last PCIe slot. That mostly doesn't matter now except for a 1x slot or so for an upgraded WLAN/NIC or aux hardware, a lot of which is perfectly obtainable with USB instead.

 

The significant downside to mATX is that's usually the budget category, so finding premium mATX boards is difficult. Asus sometimes puts out interesting mATX boards, the most interesting I owned was their x79 HEDT mATX board that I ran SLI 780Ti's in. There is an X670e AM5 mATX board that Asus put out that's quite feature rich, but that's not common and they're unlikely to make an X870e version (its also price gouged or out of stock circa a year ago).

 

Personally, I've recommend for a while and just finally got one in hand to build a system in, the best mATX case is the Asus AP201. Its also regularly between $55-$75 USD. It falls into that perfect ratio of size that can house the most extreme hardware, as long as its with a mITX or mATX motherboard. Top mounted 360mm AIO compatibility or a giant air cooler and plenty of room for the biggest of GPUs with full sized PSU support.

Or in short,

 

mATX vs ATX is just a form factor, or size in other words,

 

these sizes are important to spec, because then you can have compatibility between cases,

 

where small cases might not fit ATX or EATX motherboards because they just physically can't,

 

in terms of featuers mATX can have similarly rich features as other bigger motherboards,

 

though due to size there are certain limitations for mATX motherboards,

 

they can be high quality/high end, what's different is for example:

• Spacing between expansion slots
• Clearance on things like M.2 where smaller boards are more likely to have things like M.2 and other expansion slots located under GPU
• Feature count -> amount of expansion slots or M.2 slots a motherboard can have
• Aesthetics -> small board inside big case can half the time look weird, but not always
• Flexibility for balance of features -> if the space is limited there are chances some features have to sacrifice other ones -> big heatsink can obscure space for M.2 ports/power ports/RAM slots/etc.

 

TL;DR: it doesn't really matter half the time, because even mATX can be high-end enough and feature-rich enough to satisfy all your needs, if you choose the right model. (+ smaller boards can be just as good while also sometimes being cheaper, because they need less material to make smaller boards)

[Agall]

20 minutes ago, podkall said:

Or in short,

 

mATX vs ATX is just a form factor, or size in other words,

 

these sizes are important to spec, because then you can have compatibility between cases,

 

where small cases might not fit ATX or EATX motherboards because they just physically can't,

 

in terms of featuers mATX can have similarly rich features as other bigger motherboards,

 

though due to size there are certain limitations for mATX motherboards,

 

they can be high quality/high end, what's different is for example:

• Spacing between expansion slots
• Clearance on things like M.2 where smaller boards are more likely to have things like M.2 and other expansion slots located under GPU
• Feature count -> amount of expansion slots or M.2 slots a motherboard can have
• Aesthetics -> small board inside big case can half the time look weird, but not always
• Flexibility for balance of features -> if the space is limited there are chances some features have to sacrifice other ones -> big heatsink can obscure space for M.2 ports/power ports/RAM slots/etc.

 

TL;DR: it doesn't really matter half the time, because even mATX can be high-end enough and feature-rich enough to satisfy all your needs, if you choose the right model. (+ smaller boards can be just as good while also sometimes being cheaper, because they need less material to make smaller boards)

mATX usually has the largest gap between bottom and top ends, since its usually the form factor at the bottom. On the low end, the variability is insane, like recently choosing a mATX AM5 B650 board for a new build, having to dissect down to the wiring of the rear USB ports for a machine where there's a lot in use.

[podkall]

1 hour ago, Agall said:

mATX usually has the largest gap between bottom and top ends, since its usually the form factor at the bottom. On the low end, the variability is insane, like recently choosing a mATX AM5 B650 board for a new build, having to dissect down to the wiring of the rear USB ports for a machine where there's a lot in use.

it depends, you can still find high-end mATX for use-cases beyond your expectations,

 

like this beast: https://www.newegg.com/asus-tuf-gaming-b650m-plus-wifi/p/N82E16813119594?nm_mc=AFC-RAN-COM&cm_mmc=afc-ran-com-_-PCPartPicker&AFFID=2558510&AFFNAME=PCPartPicker&ACRID=1&ASUBID=&ASID=https%3A%2F%2Fpcpartpicker.com%2F&ranMID=44583&ranEAID=2558510&ranSiteID=8BacdVP0GFs-du2IoTDTOBeWiNqGWyUl3A

 

ASUS TUF B650M-PLUS

 

Plus series have minimum 12+2 power stages, this board in perticular has PCIe 5.0 M.2, slightly more audio connectors than your regular 3 choices, USB rich I/O panel, both rear and front USB-C support, second 16x PCIe supports 4x mode, just 2 M.2 slots but previously mentioned one is 5.0, etc.

[leveller]

Thank you very much all.

I feel really confident to build my first Steam Machine for the TV now. I only need 1 M2 slot, a PCIe slot for the GPU and 2 slots for the RAM. Seems like a no-brainier to reuse everything as a console replacement.