Turns out that Hynix strap from BuriedOne is the same one bundled with the new version 1.6 of PBE. LOL. The latest version of Polaris Bios Editor v1.6 from jaschaknack makes it simple to apply the right performance timings for your card. With the 'One click timing patch' option it will apply the bundled performance strap to the correct timings. I tried it with several brands of RX 570/580with Hynix, Elpidia and Samsung memory and they all now get 29 M/s+ stable. Much better than randomly copying timings from the diffrent straps. Some cards like the Sapphire Nitro+ have two diffrent sets of straps from diffrent brands of memory and PBE will corretly detect and apply the right strap to the right timing. Great update!
https://github.com/jaschaknack/PolarisBiosEditor
Yeah I like those names, "Good Elpida timing" https://github.com/jaschaknack/PolarisBiosEditor
Only true name has Uber-Mix But there are Hynix and Samsung memories that they aren't supported. Also it won't work with every card, those timing strap aren't the best, beware mostly with Hynix. 8GB Hynix can do much more with better timing.