Gigabyte have always had a bad rep for their GPUs
There was a period they had a pretty decent rep for their GPUs in the UK - though weirdly in other regions they've not had a great rep for their GPUs and lately they've been pushing out some lacking products. I remember when they switched a bunch of Fermi series SOC cards from the ME to UK market and the failure rates were abysmal
and if you looked at customer reviews on the US stores they were really poorly rated. (While the original UK stock were solid).
Same with their motherboards really - there was a time when they made really good quality boards with innovative features, these days they are kind of half-arsed offerings more often than not
I've dealt with a few of their more recent AMD and Intel boards with silly BIOS gremlins, etc.
The Gigabyte 780GHz edition was up there with the best GPUs I've ever had - albeit about the time I stopped using it I think the core was starting to degrade - I've not gone back to check - but it was running with the clocks and voltages pushed to the max to be fair.
EDIT: And I say that as someone who more often than not buys Gigabyte.