Mini ITX vs mATX

[LateJuly]

Is there that much of a difference between the two?
In June-July I'm planning on getting an i5 7600k or one of the new rysen 5 (still waiting for an AM4 MiniITX) and overclocking it.

The problem is that I want something small but I cannot seem to find any mATX cases that I really like except for 1 but there are plenty of miniITX cases I really enjoy, I'm just worried that I'll miss out on performance because I'm choosing to get a miniITX over a mATX and less airflow through the case.

I'm planning on getting 16gb minimum ddr4 ram and a full size GTX 1070.

TLR
What are the major differences between miniITX and mATX?

 

[XaveT]

The only real difference is the size of the board. Mini ITX boards are 6.7in x 6.7in (170mm x 170mm) in size, and Micro ATX are 9.6in x 9.6 in (244mm x 244mm). Wikipedia has details and a size comparison picture (https://en.wikipedia.org/wiki/Computer_form_factor)

Because of the size constraints, most mini-ITX boards have a maximum of one expansion slot, usually a 16x PCI-E. mATX boards have room for two double-slot 16x PCI-E cards, or more likely, a 16x PCI-E and some 1x, 4x ones. If you will only EVER have one expansion card, then mini-ITX is great. If you need expand-ability, mATX is better.

There used to be a "differing quality" prejudice against mini-ITX, but these days most of the components are exactly the same. So there won't be bottlenecks or anything in choosing a mini-ITX board (I am assuming adequate cooling, smaller space does mean harder to cool).

Edit: Spelling and words... it's late.

 

[raisonjohn]

Major differences between mini-ITX and mATX considering your planned components (i.e., Z270 chipset):

ITX = 2x RAM slots up to 32GB max. | mATX = 4x RAM slots up to 64GB max.

ITX = Most have 4x SATA 6Gb/s ports; some have only 2x | mATX = Most have 6x SATA 6Gb/s; an Asus model has 4x (but 2x M.2)
Both ITX and mATX (Z270) have at least 1x M.2 socket (with some models having 2x).

ITX = Only 1x PCIe x16 slot (multi-GPU not possible) | mATX = All have at least 2x PCIe x16 slots (mostly CrossFire only, some SLI)

ITX = Most have only 2x Fan Headers (some have 3x) | mATX = Most have 4x to 5x Fan Headers (some have only 3x)

ITX = All only have 2x USB Internal Headers (1x USB2.0, 1x USB3.0) | mATX = Most have 3x to 4x USB Internal Headers

ITX = All have Built-in Wi-Fi | mATX = Almost all do not have Built-in Wi-Fi (except for an Asus model)

And, obviously, ITX = smaller | mATX = larger

 

[lightc]

The only big disadvantage of mITX is that you loose multi GPU support, other than that, no major tradeoffs on small size boards.
Only thing I'd consider before buying case is what cooling you can fit in to it, some ITX cases are limited to very low profile coolers only and those won't handle overclock temperatures well, though, they will be fine with stock clocks.