MB don`t recognize 512MB of RAM

[LANMI]

Hi

My computer have 1GB of ram memory installed.My friend gave me one modul with 512MB of ram.When i place it in my motherboard and turn on computer my computer recognize only 512MB of ram.What should i do to have 1.5GB of ram?
This is my motherboard http://www.gigabyte.com/products/product-page.aspx?pid=2409#ov

 

[Eduello]

Different sticks often refuse to play together. Try to set the timings and voltages of the sticks to the same values in BIOS.

 

[LANMI]

Can you explain me what should i do when i enter in BIOS to set same timings and voltages?

 

[Eduello]

Go to BIOS, and to advanced settings, then go through all the settings until you find the part that allows you to change your speed, timings, and voltages.