Changing Ram frequency,

I'm really bad at computers, but my pc keeps crashing i assume because of the ram frequnecy after doing some revision..

but i cannot find the option in my bios..

my pc is:

http://desmond.imageshack.us/Himg26/...png&res=medium
et1862

Computer memory upgrades for eMachines ET1862 Desktop/PC from Crucial.com

Does anyone know how i can find the memory frequency, thank you