Your GPU dips correlate to your highest FPS on the graph.
Try one more thing for me. In your Nvidia control panel (right click desktop you'll see it) go to manage 3D settings and scroll down to power management mode. Change that to prefer maximum performance, reboot, and see what that does. This should theoretically tell your GPU to not drop from 3D clocks or boost at all no matter the load on the GPU.
Can you tell me exactly what's going on in the screen when that happens and what game exactly you're playing for the graphs above? With the graphs perfectly lined up it's showing an exceptionally high frame rate during those dips so usually I only get something like that when I'm in a menu or loading screen, sometimes when looking at an easy to render area like straight up at the sky. If this is the case depending on the game at hand I'd try limiting your frames if possible to something like 200. I can't see what your average frame rate is but it looks like you're going from like 80-110fps straight to 347 causing your hang up. Even my machine has issues when doing that, especially in online multiplayer games (except CSGO). That is a totally different issue all on it's own. Try the above two options before spending on a PSU.
As an explanation of what I'm talking about, online games especially FPS games have something called a server tickrate. In Battlefield 3, 4, and 1 you can see it will say 30, 40, or 60. This means that the frame calculation is at 30, 40, or 60. Now when we run at 120fps on a 60hz server that means our frames server side are being calculated at half the rate at which we are rendering and backend trickery does the calculations for hit detections, global physics, etc. To be more specific you might have heard somebody complain about terrible "netcode". This is what it's referring to, especially in Battlefield. This is also happening while taking into account your total latency to server, and back to you through the net. If you're at 100fps then shoot to 347 for whatever reason and back yea that's definitely going to cause some problems. I get this in Rocket League all the time. Also, frame rates shooting that high while your CPU is loaded pretty heavy would actually introduce a temporary CPU bottleneck. So let's try those two things up there and see what happens. Prefer max performance in NVCP, and a frame cap of 200 if possible (don't use vsync).
