Ok. Let's make something very clear: If screen tearing is your issue it is caused by you overdriving your fps above your monitor's framerate. If you want to run 300 fps on a 75hz monitor, you will have tearing. That's the tradeoff. Locking your fps to your monitor's refresh rate (75) will not cause tearing, it will eliminate it completely. So I'm not really sure what you're talking about, when you said as soon as you locked your fps to 75, you got tearing. That's impossible. Tearing is caused by framerates that are HIGHER than your monitor's refresh rate. Professional/high end gamers often run framerates much higher than their monitor's refresh rate to reduce input lag. But they have to deal with screen tearing in order to do it because that's what causes screen tearing. If you want to eliminate screen tearing, limit your FPS to 75fps. This will cause screen tearing to be nonexistent. If you want to reduce input lag by overdriving your monitor, then you WILL have screen tearing. There is nothing you can do about that. Let's get down to reality though: Minecraft is poorly coded. You're constantly going between 400 and 150 fps. That's going to make input lag inconsistent which is worse than a high average input lag. What you need to do is limit your fps to whatever your computer can hold without dropping any lower. If your minimum framerate is 150, lock it down at 150. If it's 100, lock it down at 100. This will get you the highest possible framerate, without having inconsistent framerate, which causes inconsistent input lag. I'm giving you the benefit of the doubt here, that you can actually perceive and are sensitive to such things, because I am too. I suspect that what you are feeling here is a combination of inconsistent input lag, and inconsistent screen tearing, which is caused by your UNSTABLE framerates.
All that being said, you can't see a difference between 400 and 75 fps on that monitor with your eyes. It just isn't possible. If you do the above, and lock the fps to your minimums, you will still get screen tearing. There is nothing you can do about that, except buy a faster monitor (144hz is the cost/performance sweet spot.) So you will still get screen tearing, but if you want to eliminate screen tearing, you will need to lock your fps at 75 to match your monitor's refresh rate. Remember, you will never EVER see more than 75 fps on that monitor, no matter how many fps you are getting in game. The ONLY reason to overdrive the fps above the monitor's refresh rate is to reduce input lag, and you have to trade off with that because you will get screen tearing.
So let's break it down simply. Your goal is to have STABLE fps and input lag. You have a couple of choices:
1. Lock FPS to your MINIMUM framerate for each game. This will reduce input lag, while also keeping it stable. You'll still only ever see 75 fps with your eyes. You will have screen tearing.
2. Lock your FPS to 75fps for all games. This will maintain a stable amount of input lag (while being slightly higher, but your brain can adjust to it) while eliminating screen tearing. You'll still see the same 75 fps with your eyes as #1.
3. Buy a faster monitor, then do 1 or 2 with it, and it's faster refresh rate.
There is no mysterious problem you're having here. Nothing is wrong with your hardware. You're simply dealing with reality. As a person who is also very sensitive to input lag and framerates, I can tell you these are your options.
(This is all discounting what I said in my other post above, because the video didn't include minimum framerates numbers. You could still be dropping to 40 fps without realizing it, and feeling the choppiness there. Working with the info I've got. To determine that, do what I said in my other post above, and learn what your true minimum framerate is.)