I just picked up a backup MacBook and it came with 2x1GB sticks. I tried putting 2x2GB sticks in but it wouldn't turn on, just a white light. So I try just 1 2GB stick, still just the light. So I tried it with 1 of the original 1GB sticks and a 2GB stick and boom, chime. For some reason it refuses to turn on unless one of the original sticks are present in the machine. Any ideas? I put 2x2GB into my Mid-2007 machine (only 3GB supported but runs fine with the 4GB installed). Any info is appreciated. Thank you!