I will try to respond in my best English:
First off: Awesome cooler, the Thermalright Peerless Assassin is unequaled in air cooling.
But it's gonna take up a lot of space in your mini-ITX case. It wil fit, but it will definetely be the center of attention when you look through the window.
You don't need to add the thermal paste, because it's included with the cooler.
Speaking of the size of the case, it will only allow a PSU of maximum 14cm. The ATX PSU you chose is already too big. So I recommend to look for an SFX size PSU as the case is probably designed for that. An ATX with a maximum of 14cm is also possible, but the information about measurements is sometimes difficult to find.
The PSU is also a bit low on the
tier list.
Check out this Corsair that scores higher and will fit your build better:
Corsair SFX 750W
Your motherboard is a good choice as it supports PCIe 5, which your GPU uses.
But the memory stands out with the low clock timings of 36ms. And I'm not sure if they will fit under the Peerless Assassin. Check out these
G.Skills.
About the M.2 drive. I would pick the
Lexar NM790 with much better performance in reading and writing for a lower cost.
For the rest I wish you good luck with the build. Building an mini-ITX build is a challenge in its own. It will involve a lot of planning and replanning, routing and rerouting, you'll wish you never started and wanna quit and then pick it up again and start over (my own opinion).
