Problem solved with the Media Creation tool downloaded from the link in the bottom here, it works fine, great tool indeed :)

I'm afraid it can't be the passmark utility, because I've installed it after I had notice of the problem at my PC; the purpose was try the sdd performances and other components to find out the cause...

I bet you never heard of that... every time i turn on the computer, everything runs slow, very slow, like if in place of my Samsung 850 pro SSD, there would be a floppy disk unit... but, and this is...