If that doesn't work, the next step is to replace the RAM - preferably with sticks that you've seen working in another computer, so you can be sure they're good. Then reinstall, reassemble and reboot, and see if anything changes. I like to use a pink pencil eraser to rub the RAM contacts clean of scuzz, and use a soft, dry toothbrush to brush the rubber crumbs off the RAM contacts and clean the inside of the RAM socket. The process for installing/removing RAM on the earlier A1181 Core Duo MacBook is identical. The first thing to try is to reseat the RAM correctly: Have you been playing arond with RAM recently, or has the computer gotten knocked around? Intel-based Mac Power On Self Test RAM error codes When the computer has a RAM issue (like the RAM's failed, or the computer can't detect it, or it can detect it but it's an incompatible type), hitting the power button causes one or more beeps, sometimes accompanied by a blinking sleeplight: Unless you are a Professional the time spent discovering this is nauseating.It sounds like something's going on with your RAM. In the past I have found, after many days of trail and error, that the RAM may have had ESD damage and cause erratic behavior. If not live with one stick, the highest your machine will take. If slot is bad, use the screw solution or sometimes it will take a lessor stick (if you have one). If the slot, try loosening the screws that hold the slot in place - crazy, I know but it can work.
Now you have known good or bad sticks or known bad slot. Take one stick only, try it in both slots to check out both the RAM and the slot.
Remove the RAM, use canned air and blow the slot out. Now you need to test if a slot has gone bad or partially bad. You are correct, and did the right thing. OK the three Beeps are a RAM issue, as you already know.