Do you want a small, but fast system? Mini-ITX offers you a versatile base that doesn't sacrifice too much functionality. For this reason we're discussing thirteen current Mini-ITX motherboards from every price segment.
These days it's possible to build a Mini-ITX system that performs excellently, despite its small size. GPU and CPU manufacturers are emphasizing improvements in power consumption more and more. This means coolers can become smaller, which makes more compact graphics cards possible. Since the last generation of graphics cards we've been seeing relatively fast Mini-ITX graphics cards, such as the GTX 970 and the R9 Nano. Full-sized graphics cards with a length of 30 cm also fit just fine in Mini-ITX systems, thanks to a large and growing number of cases that support such a card. They come in varying levels of compactness, ranging from just large enough to fit a long graphics card to even larger than micro-ATX cases.
We've established that you won't sacrifice a lot of performance if you choose to build a Mini-ITX system, but what do you sacrifice? In the first place you'll be limited to a single GPU; the ITX form factor simply doesn't offer space for multiple graphics cards. You'll also have less installation space, e.g. for hard drives, but there are certainly models that can fit more than two. You'll also be limited to smaller air coolers for the processor, but many Mini-ITX cases support water cooling.
The motherboard itself also has some limitations. Even though Mini-ITX boards feature most of the functionality of larger boards, there isn't enough space to implement everything at the same quality-level. The amount of phases for the CPU power delivery system tend to be lower compared to larger motherboards, which makes overclocking (and sometimes even stressing a normal high-end processor) harder or impossible.
You can compensate for such a limitation by using a larger case, which will have more room for cooling. This test also features ITX boards that allow you to overclock - some even support extreme cooling methods such as LN2.
The most important thing you lose when going for a Mini-ITX board is money: Mini-ITX motherboards are relatively expensive in comparison to (micro-)ATX boards. Many cases for this form factor are also not cheap, sometimes you'll even need a relatively pricey SFX power supply. The added cost of a Mini-ITX system becomes quite high this way: it's the price you pay for a compact and powerful PC.