You can't easily tell which version of the Gigabyte Gaming Edition 970 1.0 hardware you have. You need to install it and use something like GPUID to identify what memory is on the card. Of course this all assumes my theory about which ones work (Hynix) and which ones don't (Samsung) hold true, and it's not some weird BIOS variation.
I noticed the cooling fins are slightly different between the two cards I have at present (one good - Hynix, and one bad - Samsung) but it's very subtle. Perhaps it's evidence of different sub-manufacturers?
Glad you got a good one Kray. Maybe you could run CPUID up and let us know what memory you have on your card?