05 Oct 2010 at 14:57 - 4
mATX motherboards are only a little smaller than full ATX and they can fit into full size ATX cases.
mATX cases cover a broad range of sizes. On the larger end (mini tower) they are only slightly shorter than full ATX cases and can take all the same components as full ATX. On the smaller end (SFF - small form factor), there can be, depending upon the particular case, a few things to keep in mind:
1. some SFF cases have non-standard power supplies which can't be easily upgraded, so make sure that the PS is hefty enough to run the components you want to use. It may be hard to find an SFF case with a non-standard PS that can handle a GTX470 or HD5870.
2. some SFF cases can only handle low-profile cards. That can limit your choice of video card. Even some cases that can take full height cards, are resticted in the length of cards they can accept. It's unlikely that a GTX470 or HD5870 would fit in any SFF case.
3. Cooling. Maintaing proper air-flow is important. Many SFF (and regular) cases come with fans and shrouds specifically designed to assist the airflow in the particular case. Make sure that cables and other things don't block vents, etc.
4. In some SFF situations there can be unexpected component alignment problems. Several times I've had cases where some component has had problems properly fitting over the front panel connector block, once the connections are made. I've also had optical drives hitting against motherboard components. It's difficult to know in advance what sort of these problems may come up.
Genrally speaking, if you want to go to the smaller/SFF end of the size spectrum, you will have to compromise on performance. You may want to stick to the larger, "mini-tower" end of the size range to fit the components you want.
Btw, many of the latest SFF cases are designed to take only even smaller ITX motherboards. These systems are generally on the low-power end of things.