Corsair CP-9020057-EU AX Serie AX1500i ATX/EPS 80 PLUS Titanium 1500Watt, Digital, Netzteil, EU
this one or the Lepa 1600w?
for 4x R9 390?
For 4x390, 1500W is enough.
1500W is even enough for 6x390 if you use the -100mV undervoltage. That will consumes about 220W each.
The 1500W power supplies are usually not single rail, so you have to distribute the power properly among the rails.
That is very important. If the power is not distributed properly and within the limits, the power supply will crash and the computer will restart.