bios ram fsb speed?

i have a 512mb winbond buffalo 3200 in my dad's mn31n. the weird thing is the frequency it says the ram is running at is 280. the fsb is at 135 or 140 right now. something liek that. but i dont know why the memory is at 280? i mean its not dual channel or anything. just regular on stick

just wondering if its suppose to be like that