Chosen Solution
Hello there, so the problem started a few days ago, two months after I upgraded one of my RAM with a 4GB one (6GB total now) and replaced my HDD with an SSD. The problem first occurred when watching videos on YouTube, the entire system freezes and the audio from the video’s last second repeats until the system resets itself. The problem now occurs even if I’m not watching a video. The problem then progressed to beep 3 times and pause and green/black stripes of pixels appearing, which I know is a RAM problem, and I’ve reseated the RAM and the beeping ceased. But the freezes and broken pixels still occurs. The problem can be triggered when I move the system, or when I apply pressure on the laptop. I am unsure how to deal with this. It could be a GPU, a logic board, a RAM or a dust problem. Some say you can fix this by reverting back to the original RAM but I would like to know all possible solution before resorting towards that. If there’s additional inquiry to narrow down the problem, please do not be afraid to ask, I would prefer the most accurate response. Edit (16 mins. after post): Under my keyboard, some keys are dirty and my right Shift key feels very “weird” (sticky feeling) when pressed, which could be dust or grime stuck beneath. Not sure if there’s any correlation with that and my issue but any problem is worth pointing out. Edit 2 (20 mins. after post): In a grey background, I can see pixel flickering with at the top half of the screen. There may be a correlation in there and my freezes and crash. Honestly I’m unsure if the flickering is a huge deal or not.
Although it works, upgrading RAM with different size sticks is not recommended as it causes overheating since workload is not evenly distributed. It would be reasonable to return to the original configuration for testing purposes and if that solves your issues keep that configuration or consider upgrading both RAM sticks. In my opinion this would be the first step to take before anything else.
I think you’ll need to take the logic board out to inspect it for liquid damage. From what you’ve posted with the keyboard having sticky keys it likely had a soda spilled. Follow this IFIXIT guide: MacBook Pro 13" Unibody Mid 2012 Logic Board Replacement look for discoloration and staining. If you see any areas take a good clear picture and post it here for us to see. Adding images to an existing question
