Hello i just like to throw my 2 cents in .
Buying a Xeon may seem like a good option, but you get more bang for your buck with a i7 + you have OverClocking capabilaty…
Also the socket for your motherboard is somewhat outdated and you should heavily consider a LGA2011 or Xeon`s equal socket instead.
This will allow for you to upgrade should you want to in a year or two.
Futhermore the PSU you have chosen is not going to give you a system running at optimal performance.
400 GPU + 80 CPU + 7 HDD + 3 RAM = 490 Watt.
That’s the power usage of the hardware you posted, now add power usage from stuff like Fans, Front panel, USB, and other internal/ external devices.
You simple won`t have the power to run it properly and you left with a machine that’s not running as fast as it should.
Never scimp on your PSU, sorry to “trash” your build but IMO you can make some smarter choices.