MBP 15" Late 2011: Display glitch, blue lines, shut downs.

I think you’re hitting a few different issues when combined given your usage is creating your problems.

First yes! You need to replace the HD SATA cable. The 2011 models cables are just not up to handling the higher data I/O your SSD is able to push. Here’s the needed cable MacBook Pro 15" Unibody (Mid 2012) Hard Drive Cable And yes! This is the 2012 model which is designed to support the full SATA III (6.0 Gb/s) data throughput your system is able to run at. In addition you want to apply a strip of electricians tape on the uppercase where the cable crosses over. Next, the mid-plain plastic clips need to be inspected (two black clips to supports the bottom cover. You’ll want to make sure the one nearest the optical drive is intact. I would strongly recommend you place some foam tape on the optical drive to the left and right where the cable folds down to the drive just to offer a bit more protection from the bottom cover pressing on the cable if you bang the bottom cover. And lastly, You don’t want to damage the cable when you fold it! You want nice arcs not sharp folds. Over bending damages the thin foil wires within the cable.

The next issue is your SSD. You need to upgrade to a faster and larger SSD. The MX300 while a good drive has a slow write and housekeeping process. It was a good drive when it came out but SSD have gotten a lot better in the last few years. Whats happening is your drive gets bogged down, which in turn effects virtual RAM and then cascades to your real RAM that your GPU is also fighting for access. I’m suspecting given what you are doing you have a lot of data churn and you likely have a very full drive. Overtime, your SSD need to do wear leveling moving lest used block to higher used blocks so when you have a drive that has less free space it has to work harder to do this and if you have lots of stuff being moved about the SSD tells the system it needs to wait. this then causes the CPU into a bit of a race condition as it can’t make the updates as fast as you are expecting the system to do.

This is the likely cause of the blue lines and the overheating the SSD & system is also dealing with that then causes your system to shut down.

Most of the time I recommend to have more than 1/4 of the drive unused as the OS and your apps need space for virtual RAM, caching & paging.

When you are using deep files like video or music editing and modifying them you really need more scratch space. Here I strongly recommend 1/3 free so you need at least a 1 TB drive, if you can swing it I would go for a 2 TB drive. These larger drives also have better performance as well!