Hi, i just started mining with claymore. 5 RX480 red devils, and on of them keeps hashing low, i copy what im getting

ETH - Total Speed: 102.287 Mh/s, Total Shares: 139, Rejected: 0, Time: 01:35
ETH: GPU0 4.220 Mh/s, GPU1 24.774 Mh/s, GPU2 24.149 Mh/s, GPU3 24.665 Mh/s, GPU4 24.718 Mh/s

Can you guys help me and tell why getting that low hash rate

Thanks