The current within a single cable is something like 25 A according to der3uer's measurements. That's crazy for those thin cables. So if current distribution is so uneven then no cables will be completely safe IMHO.
All 12V-2x6 GPU power cables are aftermarket third-party cables. Nvidia doesn't make or supply one because PSUs have different pinouts (or may not be modular in design at all). This isn't any different to the previous situation of PCIe 8-pin power connectors on GPUs that don't come with 8-pin cables.
They do ship an adapter for older PSUs.
All of those cables and the adapter are all using the same 12VHPWR connector as standardised by PCI-SIG, with the same gauge wire. I find it highly unlikely that any of them are more safe than any other.
We really need to get out of the mindset of blaming non-first-party stuff unless one can actually demonstrate an issue with a specific product, such as CableMod's (rightly) recalled right-angle adapter (which wasn't a cable, by the way).
At the end of the day this connector has a 10% margin of safety, while a PCIe 8-pin connector had a 92% margin of safety. It is incredibly delicate, much more prone to failure, and will result in a much more spectacular failure when it does fail.
It boggles my mind that it hasn't been written off and replaced yet.
The cable and the connector are standardized, and no evidence of noncompliance has been demonstrated yet. ¯\_(ツ)_/¯
Also note that the only first-party cable NVIDIA provides is an adapter for converting between four 8-pin PCIe power connectors and the 16-pin 12V2x6 power connector. They do not provide a 12V2x6 to 12V2x6 cable nor a 12VHPWR to 12V2x6 cable, you're left with your PSU manufacturer's or other third parties' cables in those scenarios (which would include the reporter's).
I will say that it's regrettable that even derbauer's analysis was basically "idk man looks good to me". He did use a cable from the manufacturer of his PSU however at least for his own testing, so if you'd consider that a first or second party product, there you go.
