I found that i7 8700k on begining was
400 euro than on end of april it was
believe or not 280 euros and now is
420 euros?
280 Euro for a new 8700k is a great deal. Around 400 now in Europe.
I dont get it is there a month or a
day in year that is better to buy
these stuff?
There are Black Friday equivalents in Europe a.k.a. Cyber Mondays usually in November / December. Prices also drop when a new line of products is (or is about to be) released. One would expect a 5-10% drop normally; with 9900k having just arrived, there should be a small nudge in Intel processor prices.
There are always Christmas / New Year deals to consider, you just need to be vigilant. Google tech deals, you might get lucky. There must something similar to this for Europe:
https://www.reddit.com/r/buildapcsales/
When it comes to SLI / Crossfire. UE4 does not support it natively as far as I know. Not sure what’s the situation for VR - not my field.