If you see "Unknown Device" in Device Manager after installing everything, it is likely the ACPI or SMBus controller. Re-running the Chipset installer usually fixes this.
Visit the Gigabyte GA-G31M-S2L Support Page.
To get your system fully functional, you will need these specific drivers:
Before downloading anything, check which version of Windows you are running. The GA-G31M-S2L officially supports: Windows XP (32/64-bit) Windows Vista (32/64-bit) Windows 7 (32/64-bit)
The "Intel INF installation" driver. Install this first as it helps Windows recognize the motherboard components. Audio: Realtek ALC883 High Definition Audio driver. LAN: Realtek 8111C/8111D(L) Gigabit Ethernet driver. VGA: Intel Graphic Media Accelerator (GMA) 3100. 3. Where to Download (Skachat)
If you are upgrading your CPU (e.g., moving to a Core 2 Quad), you may need BIOS version F9 or later. Download this only from the official Gigabyte site to avoid "bricking" your board.