An ITX motherboard is a smaller version of an ATX motherboard. An ITX motherboard typically has only two expansion slots for cards, compared to the four on an ATX motherboard.
Some motherboards that are designed for miniaturization have only one expansion slot, making it difficult to install a larger graphics card. For this reason, some people choose to buy a separate graphics card for their ITX computer.
ITX motherboards usually have fewer RAM slots than other types of motherboards. Most miniaturized PCs use 1GB or 2GB of RAM, and few require more than 4GB.
Because of this, most ITX systems only have one RAM slot. If you need more than 1GB of RAM, you’ll need to either buy a second memory module or upgrade your motherboard to an ATX or mATX model.