So basicly get a MSI X99S SLI and a seperate WiFi module and a 5 euro bluetooth adapter and your done. Minus a few leds. And ofcourse 1 pci-e x16...
The 290x being for 1080p and the 390X for 4K has to do with memory i guess. 290 ussually have 4GB and the 390 have 8GB. Looks like 4GB won`t...