Chosen Solution
I recently got a mid-2010 MBP. It has the usual three beeps on startup indicating a RAM issue. The previous owner had bought two additional RAM chips, but this didn’t fix the problem. So I got 4 RAM chips in total. After trying different things, I’ve found out that all the chips work in the top slot (as in “it starts booting”), but only one of the chips works in the bottom slot. Not sure what to make of this. I would understand if none of the chips worked on the bottom slot, but this one does, consistently. My best guess is that it might be a slightly bent contact on the slot, with which this one RAM chip happens to make good contact? How would you go about diagnosing and fixing this?
OK, sometimes slots go partially bad and will take a lessor stick but not that a higher one. I’ve also had luck (and this is hard to believe) with loosening and/or tightening the Phillips retaining screws on the brackets. There are two on each side. You can see the two on the right on step # 5 of this guide: MacBook Pro 13" Unibody Mid 2010 RAM Replacement
Ram sticks form factor is very consistent and I can’t remember any not fitting properly into the slots, if one fits and works fine so should do the others. It would rather be more likely the specifications might not be the correct ones for the Macbook in question. Core2duo Macbooks from 2010 are designed to work with PC3-8500 at 1066Mhz. Do the RAM sticks you’re trying to use comply with the designed specs ?
