somebody might share Hynix AJR and Sam datasheet perhaps..?
I wonder how the optimized custom timings are related to the given minimal values in the official datasheet?
I mean how loose are the official values, are there even room for improvement below them, or custom straps simply are adjusted to the recommended official values...?
Here's an older Hynix GDDR5 datasheet.
https://drive.google.com/file/d/0BwLnDyLLT3WkeTBtekxTTloxMW8/view?usp=sharing
I don't have one for Samsung. You can also find Elpida/Micron product briefs that will have basic stuff like #of banks (usually 16) and bank groups (4).
Often you can push the official timings by ~30%. Sometimes, particularly when the RAM is not thermally connected to the heatsink, you may have a hard time pushing the timing by 10%.
http://nerdralph.blogspot.ca/2017/01/hot-video-cards.html
As has been mentioned in these (and other) forums many times, the best straps depend on the mining algorithm. ZEC is harder to optimize for than ETH since it has lots of writes and more variation in memory access pattern.
https://bitcointalksearch.org/topic/limits-of-zec-mining-1679855