Field of vertical lines all over Macbook Pro screen? (+ freezes, beeps)
Hello, everyone.
Here's my sitch: my MacBook Pro has really been acting out in terms of freezing with fields of vertical lines. Sometimes the screen will revert back to be free of the lines but remains unresponsive OR it shuts itself down and beeps. Sometimes it fails to wake up after sleep and when I attempt to power it on, it beeps. I took my Mac to a service provider and thinking it was a RAM problem, we ordered and put in new RAM. The problem persisted and then the logic board got replaced. Everything was seemingly fine and in working order when one day a kernel panic occurred and everything was happening all over again. I just brought it back to the service provider and we re-installed my original RAM that came with the Mac. It worked fine at first, but then the RAM beeps occurred again as well as the field of vertical lines that halt the whole system. At this point I'm simply confused at what could be the problem, as the Apple Hardware Test detected "no problem found," the PRAM/SMC have been reset, it booted up completely fine in safe mode, and I've run Disk Utility on Command + Recovery. The Apple Diagnostics tag also says that everything seems to be OK, but what could be the root of this problem??
Does anyone have any insight or suggestions on this? If so, please let me know. Needless to say, I'm tired of dealing with Mac issues when I really need it for schoolwork and such. (Sidenote: I also no longer have a warranty and for my logic board I got it replaced via an Apple Customer Care Code). Anyhow, many thanks in advance to anyone who might have some input on the matter!
PS. This is what it looks like. These pictures are from two separate occasions whereby the Mac froze and these distorted fields of vertical lines popped up.
MacBook Pro, OS X Mavericks (10.9)