Below is an image an link to the RAM Module I would suggest
The problems of 3 weeks ago and now are related to inconsistent performance on your Core, which causes knock on problems of high processor usage interrupting playback etc.
Therefore, there is no present need to do anything on your Bridge Mac [at least as I see it]
I would check your current 8Gb ram module in your QC i7 Mac to make sure it matched the specs as below…especially the speed…and if it does then I would simply replace the current 2Gb module with the one below
Your decision in the end
