2012 cMBP 3 beeps - how to know for sure it's RAM and not logic board?

[viperGTS]

My 2012 cMBP will sometimes not boot up and it instead does the 3 beeps thing, or freeze while i'm using it and do the 3 beeps thing when I try to boot it up after it freezes. I've done some googling and apparently this means there is an issue with the RAM. On some instances when this happens, I have reseated the RAM (basically take it out and put it back in). Sometimes, the MacBook boots up and other times I still get the 3 beeps.

Apparently, this can also signal a bad logic board, but if I'm able to remedy the issue - even if just temporarily - could it still possibly be the logic board? I just tried booting the computer right now and it worked.

I ran the Apple Hardware Test twice earlier; the first time, random black rectangles showed up on my screen and I had to restart the computer. The second time, the test completed but no errors were reported...

I want to buy new RAM if it is indeed a RAM issue, but how can I make sure it's not a logic board issue? I don't want to waste money on RAM if it won't fix the issue...

 

[Fishrrman]

What I would do before going further:

Take out both RAM DIMMs.

Mark each DIMM so you can distinguish one from the other.

Put ONE DIMM back into the "bottom slot" and close up the Macbook.

Can you boot and run this way without the beeps?
If so, you know that slot is good, and that DIMM is good.

Now, take the "known good" DIMM and move it to the OTHER RAM slot. Close up again.

Can you run this way without the beeps?
Now you know that BOTH DIMM slots are OK with this DIMM.

Next, open the MacBook, take DIMM #1 out, and repeat everything with DIMM #2.

Process of elimination...

 

[viperGTS]

What I would do before going further:

Take out both RAM DIMMs.

Mark each DIMM so you can distinguish one from the other.

Put ONE DIMM back into the "bottom slot" and close up the Macbook.

Can you boot and run this way without the beeps?
If so, you know that slot is good, and that DIMM is good.

Now, take the "known good" DIMM and move it to the OTHER RAM slot. Close up again.

Can you run this way without the beeps?
Now you know that BOTH DIMM slots are OK with this DIMM.

Next, open the MacBook, take DIMM #1 out, and repeat everything with DIMM #2.

Process of elimination...

Got it, thanks! Ideally, one of the DIMM's would be what's bad, since the DIMM slots seem like a much tougher repair.

I've been using the MacBook now for about an hour and a half and it has yet to freeze or restart on me. This doesn't make sense lol.

 

[viperGTS]

Update:

Both RAM modules worked fine on their on in both DIMM slots. I did get a kernel panic when shutting off the computer with one of them though, so I marked that one for now. (It might have been because I turned the computer over while it was shutting down...)

I will continue using the computer with the one that gave me the kernel panic to see if it happens again. If I don't get any crashes for a bit, should I assume this is a logic board issue?

 

[Fishrrman]

It could be a problem with one of the DIMM slots (not the RAM itself).
Sometimes tracking down a problem like this can be... vexing!

 

[viperGTS]

It could be a problem with one of the DIMM slots (not the RAM itself).
Sometimes tracking down a problem like this can be... vexing!

How difficult is it to fix a DIMM slot?

 

[Bart Kela]

How are your soldering skills?

 

[Fishrrman]

OP asked:
"How difficult is it to fix a DIMM slot?"

Heh, I don't think you're going to do that.
Probably requires a motherboard replacement.

BUT... if ONE slot "went bad" and I knew which one it was, I'd just put an 8gb DIMM into the "good slot", and be done with it.

 

[viperGTS]

How are your soldering skills?

OP asked:
"How difficult is it to fix a DIMM slot?"

Heh, I don't think you're going to do that.
Probably requires a motherboard replacement.

BUT... if ONE slot "went bad" and I knew which one it was, I'd just put an 8gb DIMM into the "good slot", and be done with it.

Sounds like it's a pretty difficult replacement... I do like the idea of using an 8GB DIMM in one slot though, lol.

I guess I won't look too far ahead. I still technically have not ruled anything out. It's hard to tell what exactly is wrong though!