You typically need anything from 875-925mV voltage on core for 1250 core clocks.
the mcv voltage that you changed is only the floor for the core voltage.
1140 is pretty good for 1250 core clocks. This is what I get for my config. Thread 4 and Thread 5 are for an RX570 8gb card. Keeps hovering between 1145-1170.
{
"hashrate":
{
"thread_0": 771.17,
"thread_1": 801.35,
"thread_2": 796.32,
"thread_3": 742.88,
"thread_4": 585.85,
"thread_5": 585.85,
"thread_6": 796.32,
"thread_7": 796.32,
"thread_8": 708.87,
"thread_9": 801.69,
"thread_all": [771.17, 801.35, 796.32, 742.88, 585.85, 585.85, 796.32, 796.32, 708.87, 801.69],
"thread_gpu": [771.17, 801.35, 796.32, 742.88, 1171.70, 796.32, 796.32, 708.87, 801.69],
"total": 7386.59,
"max": 7390.37
},
"result":
{
"wallet": "WALLET.219000",
"pool": "bittube.miner.rocks:5555",
"ssl": false,
"currency": "BitTube (TUBE)",
"difficulty": 219008,
"shares": 4161,
"hashes": 911292288,
"uptime": "34:56:08",
"effective": 7245.82
},
"gpu_status":
[
{ "index": 0, "temperature": 69, "fan": 78, "processor": "Ellesmere", "memory": 4096, "good_shares": 429, "bad_shares": 0 },
{ "index": 1, "temperature": 69, "fan": 78, "processor": "Ellesmere", "memory": 4096, "good_shares": 464, "bad_shares": 0 },
{ "index": 2, "temperature": 64, "fan": 74, "processor": "Ellesmere", "memory": 4096, "good_shares": 484, "bad_shares": 0 },
{ "index": 3, "temperature": 64, "fan": 74, "processor": "Ellesmere", "memory": 4096, "good_shares": 428, "bad_shares": 0 },
{ "index": 4, "temperature": 57, "fan": 66, "processor": "Ellesmere", "memory": 8192, "good_shares": 611, "bad_shares": 0 },
{ "index": 5, "temperature": 75, "fan": 88, "processor": "Ellesmere", "memory": 4096, "good_shares": 469, "bad_shares": 0 },
{ "index": 6, "temperature": 75, "fan": 88, "processor": "Ellesmere", "memory": 4096, "good_shares": 468, "bad_shares": 0 },
{ "index": 7, "temperature": 75, "fan": 86, "processor": "Ellesmere", "memory": 4096, "good_shares": 391, "bad_shares": 0 },
{ "index": 8, "temperature": 68, "fan": 78, "processor": "Ellesmere", "memory": 4096, "good_shares": 418, "bad_shares": 0 },
],
"miner":
{
"version": "jce/0.32e/gpu",
"platform": "Intel(R) Pentium(R) CPU G4400 @ 3.30GHz",
"system": "Windows 64-bits",
"algorithm": "13"
}
}