Computer circuit board, X-ray. This is the central circuit board controlling a computer, known as a motherboard. The surface of the board has numerous thin printed metal strips that connect the larger electrical components plugged into the board. The most important of these is the central processing unit (CPU) microchip seen on its heatsink (square, upper centre). Other microchips are also seen. The black blocks at upper left are where connections to the rest of the computer are made. The vertical units (upper right) are random access memory (RAM) for dynamic access to current computer activity. The horizontal strips (lower centre) are where new components are added to expand computing power.