An accelerator board is a computer peripheral that can increase processing power beyond what the central processing unit (CPU) would otherwise be capable of. These expansion boards historically carried faster CPUs and floating-point units (FPUs) that could increase the overall speed of a computer or assist in math intensive tasks. In some cases, an accelerator board would carry a newer or faster version of the main CPU. Today, most accelerator boards use graphics processing units (GPUs) to speed up visual displays and render three dimensional images. Modern zero insertion force (ZIF) CPUs can be easily upgraded without special tools, which accomplishes much the same purpose as installing an expansion board with a second general purpose processor.
The various types of expansion boards each serve different purposes, but they all use hardware acceleration to take some load off the CPU. Without hardware acceleration, the CPU generally needs to perform these tasks itself using software. This can result in an overall slowdown as the CPU goes through each calculation. When hardware is used to perform these tasks without the help of the CPU, overall performance may increase. This is especially true of graphics heavy applications and games, many of which run very poorly or not at all without graphics accelerator cards.
In the early days of personal computing, floating-point units were often used to perform math heavy tasks. Without a dedicated FPU, the CPU would have to perform these tasks itself. Some motherboards shipped with FPUs, while other had slots that the end user could install one into. Other computers required an accelerator board with an FPU mounted on it. These boards were typically plugged into the motherboard in the same way as any other expansion card.
Another early use of the accelerator board was to add an additional or improved CPU. Prior to the invention of ZIF processors, CPUs were difficult or impossible for an end user to remove and upgrade. An accelerator board provided an easy way to speed up a computer if the CPU it shipped with was not fast enough. These accelerator boards often came with increased power requirements, so the power supply unit (PSU) sometimes had to be upgraded as well.
The most common modern use of the accelerator board is for graphics processing. Motherboards often come with integrated graphics, though many users find these chipsets insufficient for intense usage. In order to play many modern video games or perform heavy graphics and video editing tasks, some type of hardware acceleration is often necessary. This usually comes in the form of a GPU, which is a dedicated processing unit mounted on an expansion card. When one of these units is installed in a computer, it can take over the graphics processing tasks from the CPU.