This card was troublesome for me too at the begining. It just wouldnt mine better when I oc it.
But I menaged to troubleshoot it and rise eth mining from 21 to 26.
I am talking about
https://www.asus.com/Graphics-Cards/MINING-RX470-4G/ this card if the post is about it.
Please, when you mention the card model, tell also what memory it equipped. For example ASUS 470 STRIX normally could be with Hynix (most often) or Elpida memory onboard, but I have a friend with Samsung (which is extremely rare for ASUS 470's)
As well your GPU clocking is too high for ETH mining IMHO. My 470 STRIXes with Hynix doing 27Mh at gpu 1080 and 1925 mem settings.
I have tried to OC the memories but it has no effect. Im using the latest claymore miner v.10. It lokks somehow the afterburner has no effect when I try to overclock the memories... Its so weird. Its like the cards are running in some auto mode. I even tried to overclock the memories to 2250 but still it ran at almost 25MH...
What miners are you using for etherium mining?
One thing i noticed the GPU is running on 1020Mhz even if I have it clocked to 1200Mhz in afterburner. Does these cards have any kind of auto mode

Those cards has Hynix memory.
About GPU clock, the mining hashrate for ETH on those cards are very dependable from GPU clock. If I set it to 1100 on example it will mine 24.5 mhs, and they can go up to 26.8 on 1290 (but not stable because of high clock for them).
When you OC cards on Afterburner you must rise power limit, rise it to max and dont worry. When you set GPU clock 1200 but power limit is 0 your card will go 1020 mhz, but if you make Power limit at max, the card will go at 1200 Mhz.
Btw dont rise mem clock so much