The board is picky about RAM. The manual specifies that only low-density, double-sided DDR3 modules work reliably. It also details which slots to populate for dual-channel mode. Ignore this, and your system may beep at you or only see half the memory.
Detailed manuals for this specific OEM board are often included in the system documentation for Acer or eMachines desktops. ECS G41T-AD - The Retro Web g41t-ad v1.0 motherboard manual
The is a micro-ATX (mATX) motherboard built around the Intel G41 Express chipset. It was designed for Intel’s LGA 775 socket, supporting Core 2 Duo, Core 2 Quad, Pentium Dual-Core, and Celeron processors. The board is picky about RAM