Apart from the back-handed bs spouted earlier, there's a couple things.
1. Yes, the psu is somewhat underpowered and running that much power is seriously not healthy for anything. You are looking at 100w cpu, 100w gpu, 50w on the mobo and rest of the pc. You can expect damage to components at the very least, at most one day the psu will go up in smoke and hopefully not take anything with it. A 1050ti can run on 300w fine, but at least 350w is recommended.
Gpus, cpus, psus should not run 99%, even if capable. It's like a car, just because it'll get 0-60mph in 5 seconds doesn't mean you mosh the gas peddle at every traffic light. Just because it can, doesn't mean it must.
Cph/gpu usage will vary. Most games I play my i7-3770K runs 45%-55% and my gtx970 runs 55%-65%. I do have games capable of taking the gpu to 99%, but the benefits of a 4k DSR are debatable over smoother game play.
1x8Gb stick of ram is @20% less efficient than 2x4Gb of ram in dual channel. If you are not maxing out either ram draw usage or ram size, then it's not much difference. Dual channel might be advisable, but single channel still works just fine in gaming as nothing is really that ram demanding. Now if you need to keep 50 tabs open in Chrome, that's a different story.
Cpu temp while gaming of 70°C with a Sandy-Bridge i7 and stock cooler is perfectly normal. Changing paste won't really change much, only a better cooler will. But if the temp doesn't worry you, it's fine and reasonable for the load.