Acer H11H4-AD (also manufactured by ECS as the ) is a proprietary motherboard used in Acer desktop models like the Acer Veriton X2640G Aspire XC-710 Veriton X4650
Since Acer often changes OEM pinouts, here is the verified breakout for the H11H4-AD.
2x DDR4 SO-DIMM slots (standard laptop-style RAM), supporting up to 32GB of DDR4 2133/2400 MHz. Expansion: 1x PCI Express x16 slot for dedicated graphics. 1x M.2 slot for SSD storage. 1x Mini PCIe slot. 2x SATA 6.0Gb/s connectors. Key Internal Headers & Components Header Name
Note: While 2666 MHz RAM may be installed, it will typically downclock to 2133/2400 MHz due to chipset limitations. Expansion & Storage Graphics: One PCI Express x16 slot for dedicated GPUs.