|"Doesn't appear there is a manual"|
To start with, you have to get the model number correct. Leaving the dash out between the 'A' & the '8' & between the 'L' & the "N' makes a huge difference. The model number *should* be GA-8SIML-NF.
And if the board is out of an OEM system (Packard Bell?), you're not gonna find the board or the manual listed at the Gigabyte website.
Apparently your board has 2 memory slots, can accept a max of 512MB DDR333 per slot & it MUST be 2.5v unbuffered.
* Supports 2 memory slots.
* Serial Presence Detect (SPD) support
* Supports a maximum memory size of 1 GB (using 2 x 512 MB memory modules)
Warning: Not all memory configurations have been qualified!
* Support only 2.5 V DIMM DDRAM configurations
* Unbuffered type support