You would need to replace the motherboard to fix the problem. If another computer's memory doesn't work and it is compatible with your computer, the motherboard or its memory slots are defective. If another computer's memory works, you know the computer has bad memory. If you can another computer that uses the same memory, take memory from that computer and install it into your computer. Try known-working memory from a separate computer

Repeat for each stick of memory in the computer, to check if any one of the memory sticks is causing the problem. If this does not resolve the issue, remove that stick of memory and try one of the other sticks of memory. If you have more than one stick of memory, try removing all but one stick of memory and boot the computer. If you have only one stick of memory in the computer, try moving it to another memory slot and then boot the computer. If reseating the memory did not resolve the issue, try swapping the location of the memory. If this works, but you have to reboot the computer several times each time you start the computer, you may still have an incompatible memory stick. Some computers may have difficulties detecting the memory at first. Try to reboot the computer two or more times. Try fixing this issue by opening the computer, removing each of the memory sticks, and placing them back into the memory slots. Sometimes when the computer is moved, or over time, a memory stick can become loose, causing errors as it's being read. What type of computer memory to use in a memory upgrade.If the computer works fine after removing the new memory, your memory is either incompatible or defective. If you've recently added or tried to add additional memory to the computer and have started getting these beeps, remove the new memory you've added to the computer. Information about ESD and proper grounding techniques is found on our ESD help page.

While in the computer, be sure you're aware of ESD and its potential hazards. Some steps below recommend removing physical parts from inside the computer.

Macbook pro 3 beeps not turning on