Might be too much OC.
Try another miner like T-Rex.
If you get same rejects lower oc.
1.62kh/watt seems a bit too high for me.
I am under 1.6kh/w, even on 2080 rigs.
20200708 06:37:50 kawpow epoch: 174, block: 1309571, period: 436523, diff: 0.337 = 1.60 Gh
20200708 06:38:05 [ OK ] 15219/15246 - 105.73 MH/s, 16ms
20200708 06:38:13 [ OK ] 15220/15247 - 105.74 MH/s, 16ms
20200708 06:38:21 [ OK ] 15221/15248 - 105.76 MH/s, 16ms
20200708 06:38:45 [ OK ] 15222/15249 - 105.85 MH/s, 16ms
20200708 06:38:53 kawpow epoch: 174, block: 1309572, period: 436524, diff: 0.337 = 1.60 Gh
20200708 06:38:58 kawpow epoch: 174, block: 1309573, period: 436524, diff: 0.337 = 1.60 Gh
20200708 06:39:53 [ OK ] 15223/15250 - 105.46 MH/s, 15ms
20200708 06:39:53 GPU #0: RTX 2070 SUPER - 20.88 MH/s, [T:69C, P:138W, F:33%, E:151kH/W]
20200708 06:39:53 GPU #1: RTX 2070 SUPER - 21.71 MH/s, [T:70C, P:139W, F:50%, E:157kH/W]
20200708 06:39:53 GPU #2: RTX 2070 SUPER - 21.28 MH/s, [T:68C, P:138W, F:39%, E:154kH/W]
20200708 06:39:53 GPU #3: RTX 2070 SUPER - 20.99 MH/s, [T:64C, P:139W, F:31%, E:152kH/W]
20200708 06:39:53 GPU #4: RTX 2070 SUPER - 20.59 MH/s, [T:63C, P:138W, F:55%, E:148kH/W]
20200708 06:39:53 Shares/min: 3.448 (Avr. 3.611); total rejected: 0.177%, Avr.Power: 691W, Avr.Efficiency: 153kH/W
20200708 06:39:53 Uptime: 2 days 22 hours 15 mins 25 secs | Algo: kawpow | T-Rex v0.15.8
20200708 06:40:07 [ OK ] 15224/15251 - 105.40 MH/s, 15ms
20200708 06:38:46 [ OK ] 28742/28837 - 133.77 MH/s, 15ms
20200708 06:38:53 kawpow epoch: 174, block: 1309572, period: 436524, diff: 0.775 = 3.20 Gh
20200708 06:38:59 kawpow epoch: 174, block: 1309573, period: 436524, diff: 0.775 = 3.20 Gh
20200708 06:39:58 [ OK ] 28743/28838 - 132.66 MH/s, 15ms
20200708 06:40:13 kawpow epoch: 174, block: 1309574, period: 436524, diff: 0.775 = 3.20 Gh
20200708 06:40:40 kawpow epoch: 174, block: 1309575, period: 436525, diff: 0.775 = 3.20 Gh
20200708 06:41:02 [ OK ] 28744/28839 - 132.93 MH/s, 15ms
20200708 06:41:04 kawpow epoch: 174, block: 1309576, period: 436525, diff: 0.775 = 3.20 Gh
20200708 06:41:15 [ OK ] 28745/28840 - 133.09 MH/s, 15ms
20200708 06:41:15 GPU #0: ASUS RTX 2080 - 26.99 MH/s, [T:55C, P:169W, F:0%, E:160kH/W]
20200708 06:41:15 GPU #1: MSI RTX 2080 - 26.01 MH/s, [T:54C, P:168W, F:0%, E:155kH/W]
20200708 06:41:15 GPU #2: MSI RTX 2080 - 26.54 MH/s, [T:58C, P:169W, F:0%, E:157kH/W]
20200708 06:41:15 GPU #3: MSI RTX 2080 - 26.47 MH/s, [T:53C, P:169W, F:0%, E:157kH/W]
20200708 06:41:15 GPU #4: Gainward RTX 2080 - 27.07 MH/s, [T:53C, P:173W, F:0%, E:160kH/W]
20200708 06:41:15 Shares/min: 1.913 (Avr. 3.561); total rejected: 0.329%, Avr.Power: 844W, Avr.Efficiency: 158kH/W
20200708 06:41:15 Uptime: 5 days 14 hours 31 mins 7 secs | Algo: kawpow | T-Rex v0.15.8
20200708 06:42:18 [ OK ] 28746/28841 - 133.45 MH/s, 17ms