Hello there I will be building new PC from scratch and I would like to have a bit of help with it since I have little experience with components. I have aprox 3100 Euros so there is planty of space for good stuff. Thanks for help. Maybe I will be finally able to have stable 60 fps on Arma

Maybe I will be finally able to have stable 60 fps on Arma

Nope. Not even a chance in hell. That is all configuration and luck of the draw. Explain what you need your computer for and folks here will help you build to your specs rather than a generic gaming pc that sucks at office tasks.

Ok, So I am planning going in to 1440p monitor in the future so far I have FHD. I have Oculus Quest thats going to be PC connected in november so I would like to have VR ready PC. About storage Since game sizes are growing each release I kinda realised that 1tb is not enough for gaming. I am also planning on streaming more and repacking maps in Stalker mod where good cpu is needed to reduce time. Since there is rtx I would love to see it on my own eyes especially in Metro Exodus. I had to really limit myself on my 970 and 4690k recently and since I have the money I would like for the first time to actually play on max on very demanding games. About cooling I am completely noob to water cooling I never tried it and I have never seen it. I thought that noctua could solve the problem.

https://www.czc.cz/246374,151820,243423,...25364/kody this is a list that my friend recommended its in the czech but you can get a picture since names of components stays the same.

Although the Noctua is a good cooler you will not be able to run a stable and significant overclock on the PC. My recommendation would be to drop to a 9700 (non K variant) and include another 2 sticks of ram for a total of 32gb, and add a 1tb SATA SSD. Also, the improvement in terms of performance in RAM clock speeds drops off a cliff after 3200mhz. Anything after that point is just to say you have it. To summerise:

I7 9700 with Noctua cooler or 9700k with AIO watercooler to overclock for future-proofing. The 9900k is a VERY good top of the range CPU but it would be unlikely you would be able to use the full amount of threads in tasks because software programs have not caught up with the times and windows is a bit poopy too. Either of my mentioned configurations would be more than plenty for the tasks described and save you some money for peripherals or anything else you require.
Same GPU as on list
32gb of 3200mhz RAM
Same NVMe SSD
Add a 1tb SATA SSD for bulk fast storage, the cost difference in SATA SSD's compared to conventional HDDs is so minimal now there is no point unless its for archival server storage.
Case looks good for airflow and cable management but I have never heard of it.
I don't know enough about motherboards to advise but that one looks cool.

I run a 9700k with Corsair AIO watercooler and an RTX 2070 with 16gb 3200mhz ram 1tb NVMe SSD and 1tb SATA SSD. Arma runs perfectly well enough CLOSE to stable 60 in and out of ops here. Other games, for example the new Call of Duty Beta, I was running comfortably at 1440p 120fps on my 1440p 144hz monitor. With the budget you have, you cannot go far wrong and either way, you will have an amazing system. Just remember, because you have that budget doesn't mean you HAVE to spend it all but your money so you do what you very well please with it. I just wish I had that budget!

Although the Noctua is a good cooler you will not be able to run a stable and significant overclock on the PC. My recommendation would be to drop to a 9700 (non K variant) and include another 2 sticks of ram for a total of 32gb, and add a 1tb SATA SSD. Also, the improvement in terms of performance in RAM clock speeds drops off a cliff after 3200mhz. Anything after that point is just to say you have it. To summerise:

I7 9700 with Noctua cooler or 9700k with AIO watercooler to overclock for future-proofing. The 9900k is a VERY good top of the range CPU but it would be unlikely you would be able to use the full amount of threads in tasks because software programs have not caught up with the times and windows is a bit poopy too. Either of my mentioned configurations would be more than plenty for the tasks described and save you some money for peripherals or anything else you require.
Same GPU as on list
32gb of 3200mhz RAM
Same NVMe SSD
Add a 1tb SATA SSD for bulk fast storage, the cost difference in SATA SSD's compared to conventional HDDs is so minimal now there is no point unless its for archival server storage.
Case looks good for airflow and cable management but I have never heard of it.
I don't know enough about motherboards to advise but that one looks cool.

I run a 9700k with Corsair AIO watercooler and an RTX 2070 with 16gb 3200mhz ram 1tb NVMe SSD and 1tb SATA SSD. Arma runs perfectly well enough CLOSE to stable 60 in and out of ops here. Other games, for example the new Call of Duty Beta, I was running comfortably at 1440p 120fps on my 1440p 144hz monitor. With the budget you have, you cannot go far wrong and either way, you will have an amazing system. Just remember, because you have that budget doesn't mean you HAVE to spend it all but your money so you do what you very well please with it. I just wish I had that budget!

Are you sure about the cooling ? In many articles I can read that even on overclocked to 5.0 ghz the Noctua went about mid 70. Plus I will have about 9 fans 3 from Fractal and Five from noctua to keep it even cooler.

Not from personal experience no. Only from material online