The 1750 MHz timing strap mod is only for cards with Samsung memory. I have a Nitro+ RX 570 4GB card with Hynix memory. I copied the 1500 MHz strap to the higher timings and get ~29 MH/s UBQ and 760 MH/s DCR dual mining. I use an overclock of 1150 MHz core clock 2075 MHz memory clock with a -96 mv undervolt and -10% power limit in Afterburner.
nonsense
1750 should work as well, too, except 1500 should give somewhat better results. However, many Hynix chips can't stand it
That must be your Hynix VRAM. All my RX 570/580 Hynix memory cards, 7 in total from Sapphire and Powercolor have a simple 1500 MHz strap mod and all get at least 28.5 MH/s.