The i9-7900X comes without a boxed CPU cooler. This CPU generates far more heat than such a cooler could decently regulate. It is therefore highly recommended to use a large air cooler or a water cooler.

It depends on whether you want to run oc. What do you want to use the cpu for? How big is your case? Without this information, you cannot make a recommendation.

In my opinion, it should be just enough. So far I have not been able to find much information on this on the web or I see contradictory data.

Ja genau. Ich würde dir dieses Kabel empfehlen: Maxxtro Netzkabel (3-Pol. Typ J, C13, 1.80m)

Hello, I am sorry to disappoint you. The processor is made for a different socket because it draws much more power and also has functions that are not compatible with the normal platform. You have to look for a motherboard with the lga 2066 socket and the x299 chipset. Or a processor with lga1151, i.e. a 7700k or similar.

http://cpu.userbenchmark.com/Compare/Intel-Core-i9-7900X-vs-AMD-Ryzen-TR-1950X/3936vs3932 Threadripper ist in Sachen Multi-Core einfach besser.

This has nothing to do with each other. The Core i9-7900X supports a maximum of 128GB RAM. If the processor needs data for a calculation or processing, it first looks for this data in the small L1 cache, if not available it looks in the L2 cache and then in the L3 cache. If the data is not in any of these caches, it must be fetched from the much slower RAM. The whole process is hierarchical: L1: Small but very fast L2: Larger and quite fast L3: Larger but slower RAM: even bigger but very slow (in relation to the cache) Hard disk: even slower than RAM. How much RAM makes sense depends on what the PC will be used for. 16GB is sufficient for games and "normal" work. By the way, the Core i9-7900X has four memory channels, i.e. 4 or 8 RAM modules should be installed for optimal performance. Greetings Chris