Socket AM4

• Support for Zen (including Zen+, Zen 2 and Zen 3) based family of CPUs and APUs (Ryzen, Athlon), as well as for some A-Series APUs and Athlon X4 CPUs (Bristol Ridge based on the Excavator microarchitecture) • Supports PCIe 3.0 and PCIe 4.0 • Supports up to 4 modules of DDR4 RAM in dual-channel configuration == Heatsink ==

The AM4 socket specifies the four holes for fastening the heatsink to the motherboard to be placed in the corners of a rectangle with a lateral length of 54×90 mm. Previous sockets have 48×96 mm. Some heat sinks for older sockets are not compatible. Some cooler manufacturers, however, are reported to be offering brackets allowing previously manufactured coolers to work with AM4, while other coolers will be redesigned. Alternatively, some motherboard makers are including both AM3 and AM4 cooler mounting holes, allowing previous generation coolers to be used. AM4 coolers that use a two-pronged bracket approach (such as the AMD Wraith Prism) to mount the cooler will work with AM4 and all the way back to Socket 754/939. == Chipsets ==

Socket AM4 is currently a base for 8 chipset models. While the processors for this socket have been designed as systems in a package (SiP), with the traditional northbridge and southbridge on board the processor, the motherboard chipset will increase the number of PCI Express lanes and other connectivity options. These connectivity options include: NVMe, SATA, and USB 3.2 Gen 2. There also exists chipset-less variations of A320 and X370, called A300 and X300 respectively, that rely solely on the I/O die integrated into the CPU; these platforms are designed solely for small form factor (SFF) systems where there is a possibility that there is not enough space on the board to fit an actual chipset; these 'chipsets' are also solely available for OEM use only and are not available for purchase with SFF boards. == Compatibility ==

In 2020, AMD faced some criticism when it was announced on May 7 that its Zen 3-based Ryzen 5000 microprocessors would only be compatible with newer 500-series chipset AM4 motherboards. This was explained as motherboard BIOS's sizes not being large enough to support the full range of AM4 socket processors. On 19 May 2020, however, AMD changed its position and stated that Zen 3 would be coming to selected older X470 and B450 motherboards via a BIOS update. This would be achieved by disabling support for some older AM4 processors in the BIOS ROM in order to allocate space to support the newer processors. AMD later officially expanded Ryzen 5000 support to 300-series motherboards in March 2022. == See also ==