You are probably using xmr stak settings here. well don't. Try out auto setup.
Vega56 @ 1450/900 = 1750khs on 110/32/2 F0
Tks Dok, now are very well
GPU2 [9] Radeon RX Vega 1450 900 53 3309 0 1764
GPU3 [19] Radeon RX Vega 1450 900 58 3270 0 1762
GPU4 [12] Radeon RX Vega 1450 900 57 4558 0 1764
GPU5 [16] Radeon RX Vega 1450 900 56 3114 0 1762