Because the H61 chipset lacks SATA 3 (6Gbps), your SSD is capped at SATA 2 speeds (~250 MB/s real-world). The manual does not hide this—look for “SATA 2.0 3Gb/s” in the storage section. The only fix is a PCIe-to-SATA 3 adapter card in the PCIe x1 slot.
The manual shows a top-down diagram. Memorize these labels: Acer H61h2-ad Motherboard Manual
If you just need the basics, here’s what the manual would tell you: Because the H61 chipset lacks SATA 3 (6Gbps),
The board requires a standard 24-pin ATX main power connector and a 4-pin 12V CPU power connector. The manual shows a top-down diagram
The H61 chipset does not support native USB 3.0. Some Acer H61H2-AD boards have a third-party USB 3.0 header (Via or ASMedia), but most do not. Also, SATA 3 (6Gbps) is missing—SSDs will run at half speed.
Your safest bet is to:
Double-check with a multimeter; if your case uses a different grouping, refer to the actual manual diagram.