Suppose you have 4.000 dollar/euro/whatever your currency is, to blow on a pc

[Pemalite]

Cut down the Radeon to the Radeon 290 with aftermarket cooling, not reference.
Swap the motherboard for a Socket 2011 board+Core i7 4930K.

Ditch the two red drives and get a single Western Digital Black 4tb.

I would also personally drop the Blu-ray burner, who uses last centuries optical discs these days? :P
I would also drop the sound card and go with much cheaper DDR3 1600mhz or 1866mhz memory.

That should save you enough cash to get a fourth Radeon 290.

And upgrade that case to something with more room.

And you basically end up my primary PC.