Great summary. Buildzoid over on YouTube came to a similar conclusion back during the 4xxx series issues[1], and looks like he's released a similar video today[2]. It's worth a watch as he gets well into the electrical side of things.
It's been interesting to think that we're probably been dealing with poor connections on the older Molex connectors for years, but because of the ample margins, it was never an issue. Now with the high power spec, the underlying issues with the connectors in general are a problem. While use of sense pins sorta helps, I think the overall mechanism used to make an electrical connection - which hasn't changed much in 30+ years - is probably due for a complete rethink. That will make connectors more expensive no doubt, but much of the ATX spec and surrounding ecosystem was never designed for "expansion" cards pushing 600-800w.
> I think the overall mechanism used to make an electrical connection - which hasn't changed much in 30+ years - is probably due for a complete rethink.
There are tons of high-power connectors out there, and they look and work pretty much the same as the current ones (to the untrained eye). They are just more expensive.
Though at 40A+ you tend to see more "banana" type connectors, with a cylindrical piece that has slits cut in it to deform. Those can handle tons of current.
> There are tons of high-power connectors out there, and they look and work pretty much the same as the current ones (to the untrained eye). They are just more expensive.
That's fair, so maybe not a complete rethink then. But definately a higher standard of quality. Right now, my experience with any of those molex type connectors (be it a 4 pin HDD connector or 8 pin EATX 12V or PCI-e somethingorother) is that they rely on the pin properly aligning with the holder on the other side, and if those aren't lined up, the pin can simply end up pushing the holder and it's wire back, instead of seating correctly. There's plenty of give and play in those cables, and it's hard to tell at a glance if all of them have seated correctly or if a holder has been pushed backwards in it's socket. I can imagine a higher quality connector with tighter tolerances and stiffer materials would lessen the likelihood of this happening, but no doubt with higher costs to PSUs and cards.
I suspect manufacturers are sensitive to price increases there, but I have to imagine tacking on even a few dollars to an already exorbitantly priced card that might melt otherwise is a good value? I guess we'll see.
Both male and female terminals are supposed to be retained in the plastic housing by little wings (locking tangs) that are very strong. The metal bits can wiggle in the plastic housing (feature not a bug -- something has to absorb the tolerances) but not retract, not without an extractor tool or an extreme amount of force sufficient to tear apart or fold the metal contact. Anyone who has tried to extract one of the terminals without the correct extractor tool can attest to just how much force this is. It's a lot, and the specs are also such that you should never get a metal pin tip meeting a metal edge if the plastic bits are engaged.
Of course, shitty out-of-spec molex clones abound. I have no doubt you saw what you saw, I'm coming to the defense of the specified design, which is ingenious and works extremely well at extremely low cost and loose tolerances when implemented correctly.
This [1] is also a good deep dive into the space covering the spec, limits, and materials details. For example:
> The specification for the connector and its terminals to support 450 to 600W is very precise. You are only within spec if you use glass fiber filled thermoplastic rated for 70°C temperatures and meets UL94V-0 flammability requirements. The terminals used can only be brass, never phosphor bronze, and the wire gauge must be 16g (except for the side band wires, of course).
And yet plenty of things around the house use far more than 800W and work fine. The secret is to use a more reasonable voltage.
30V or 36V or even 48V would leave a decent margin for touch safety and have dramatically lower current and even more dramatically lower resistive loss.
It's been interesting to think that we're probably been dealing with poor connections on the older Molex connectors for years, but because of the ample margins, it was never an issue. Now with the high power spec, the underlying issues with the connectors in general are a problem. While use of sense pins sorta helps, I think the overall mechanism used to make an electrical connection - which hasn't changed much in 30+ years - is probably due for a complete rethink. That will make connectors more expensive no doubt, but much of the ATX spec and surrounding ecosystem was never designed for "expansion" cards pushing 600-800w.
[1] - 12VHPWR failures (2023) https://youtu.be/yvSetyi9vj8?t=1479 [2] - Current issues: https://www.youtube.com/watch?v=kb5YzMoVQyw