First credible report of RTX 5090 FE with melted connector appears

https://www.tomshardware.com/pc-components/gpus/first-credible-report-of-rtx-5090-fe-with-melted-connector-appears-third-party-cable-likely-cause

by LorenDB • 1 year ago

35 19 1 year ago

tomshardware.com

genter• 1 year ago

Very interesting that both ends failed at the same time. That tells me that there was a manufacturing flaw at both ends (IE bad crimp), the connectors were made from too thin of material (again, a manufacturing flaw), or the GPU drew more current than what the connector was designed to carry.

cozzyd• 1 year ago

I think this can happen easily if some of the wires become unconnected due to the melting of the first pin, resulting in more current in the remaining pins, that the remaining connector cannot handle. Likewise, a short on the far connector could do something similar.

rkagerer2• 1 year ago

I'm always wary of any power solution that splits current over multiple parallel wires without some kind of way to limit or detect over-current in the remaining strands when one faults.

eqvinox4• 1 year ago

The problem with that is that to measure per-strand current you need to isolate at least one strand and have a current measurement shunt in it, and then either that strand will carry less current (due to the extra shunt resistance), or you do it for all strands and then all of them have worse characteristics due to the shunts. And any tolerance between shunt values would result in an unbalanced per-strand current…

So, yes, it's doable, but there's a thermal/efficiency/reliability cost.

Generally you'd just design enough margin into it so that a failing strand doesn't matter. I'm suspecting they just didn't add enough margin, maybe it's only designed to support one of the six strands failing (I would really expect at least a tolerance of 2 failed.)

Or it's really a poor design regarding the mechanical latching; can't work if all pins have poor connection…

numpad02• 1 year ago

TGP for 5090 is 575W. PCIe slot supplies 75W, so it's 500W through the connector 500W / 12V = 41.7A, or 52A with 80% derating rule. Conductors should be 10AWG or thicker.

What are go-to connectors at these currents?

BenjiWiebe• 1 year ago

You'd usually have multiple wires and split the current up. Also, if you design carefully you can let your wires get hotter than what would be recommended for in-wall wiring (what the calculators usually figure for).

If you know you'll have airflow, and the insulation is rated better, you could run them hot.

bestouff• 1 year ago

Well, obviously you can't run them so hot ...

AlotOfReading• 1 year ago

For PC components, molex mini-fits. Not sure exactly which product lines the 5090 specced, but you can get them with 10A+ per circuit.

numpad02• 1 year ago

But its cousin Micro-Fit is what melted, and it's been happening for a while, so infinitely parallelizing these sounds a bit sketchy to me.

dmitrygr• 1 year ago

I’m guessing that at some point in time, these graphics cards are going to have to fit a temperature sensor next to that connector, to safely shut the card off if the connector is overheating. A wire of a given thickness will easily carry the calculated current so wires generally don’t need sensors. Connectors are more complicated. Dust, crumbs, or oxidation can significantly increase resistance, causing rapid heating, so a temperature sensor there would actually make sense. Actually, given the past history of these connectors melting, I’m surprised NVIDIA didn’t do this already.

katmannthree• 1 year ago

Yes but that would increase the BoM by several cents on these $1k+ GPUs so it's not likely to happen.

tliltocatl2• 1 year ago

Maybe just go 24V (or even higher, it's not like the GPU connector sees a lot of switching so contact arching is not a problem). Yes, that's a new PSU, but at that rate it's going to happen anyway.

eqvinox4• 1 year ago

Yeah, more likely that'd be 48-55V, much larger space of existing solutions for that (Telco DC power, PoE and LED lighting) and likely also more efficient.

metalman• 1 year ago

I will paraphrase a comment on engineers, this time for electrical engineering "any idiot can build a power cable, but it takes an electrical engineer to barely make a power cable" original concerns bridges... edit: I should add that it is both a critical and complimentary remark, depending on the outcomes.

First credible report of RTX 5090 FE with melted connector appears

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