Advanced Communications Riser

The Advanced Communications Riser, or ACR, is a form factor and technical specification for PC motherboard expansion slots. It is meant as a supplement to PCI slots, a replacement for Audio/modem riser (AMR) slots, and a competitor and alternative to Communications and Networking Riser (CNR) slots.
Technology
The ACR specification provides a lower cost method to connect certain expansion cards to a computer, with an emphasis on audio and communications devices. Sound cards and modems are the most common devices to use the specification. ACR and other riser cards lower hardware costs by offloading much of the computing tasks of the peripheral to the CPU.
ACR uses a 120 pin PCI connector which is reversed and offset, retaining backward compatibility with 46 pin AMR cards while including support for newer technologies. It is also more cost-effective and simple for the manufacturer, since the connectors are identical to the PCI connectors...