NV 12VHPWR issues revisited

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The values change slightly each time they are plugged in, which indicates the general deficiencies of the plug connection (clamping surface, contact). Added to this is the voltage drop, which also depends on chance.

The shortcomings of the 12VHPWR connector, in particular the uneven current distribution through the cable and connector, can cause unbalanced loads where individual pins are loaded more than others. These local overloads lead to increased contact resistance and heat generation, which under certain conditions can cause thermal damage to contacts and cables. In addition, by dispensing with active balancing and splitting the power supply across several rails in the board topology, NVIDIA has itself abandoned possible protective and corrective measures. As the cards directly take over the faulty distribution of the input side, the power load remains uncontrolled, which can lead to escalation under the wrong conditions.

This situation shows how several factors can interact: The inadequate plug connection as a starting point, the resulting thermal issues as a potential symptom, and the lack of protection measures on the board as an untapped opportunity to remedy the situation. Although such problems do not necessarily have to occur, the system remains susceptible to this concatenation if the load and the external conditions coincide unfavorably.
 

MrTeal

Diamond Member
Dec 7, 2003
3,869
2,524
136
Weird that there's 5, I wonder what the extra one is for? There's only 4 input filtering caps, and 12 incoming 12V lines doesn't divide nicely with 5. Maybe they're grouping into four main 12V rails and just thiefing power from one of them (any measuring through another resistor) for the minor rails.
 

Heartbreaker

Diamond Member
Apr 3, 2006
4,742
6,247
136
Slight tangent. I just had this YT story suggested by the algorithm:


It seems that NEMA 14-50 (50 Amps) outlets used to attach home car chargers, are melting.

50 Amps is serious current, where you need perfect connections.

Suggestions are Direct wiring is better, if not, make sure you get an industrial grade outlet.
 

MrTeal

Diamond Member
Dec 7, 2003
3,869
2,524
136
Slight tangent. I just had this YT story suggested by the algorithm:


It seems that NEMA 14-50 (50 Amps) outlets used to attach home car chargers, are melting.

50 Amps is serious current, where you need perfect connections.

Suggestions are Direct wiring is better, if not, make sure you get an industrial grade outlet.
Eh... I'd probably direct wire the charger, but 50A isn't that crazy and just seems that way because at 240V it's a lot of power. It's not more than a 5090 draws really. Half the 16 year kids with their new license and and $1000 beater are running straight to Crutchfield to buy 2/0 cable and a couple 2kW amplifiers to pull hundreds of amps and keep their whole neighborhood up for hours at a time and they hook that crap up with nothing but a screwdriver and a dream.
 

amenx

Diamond Member
Dec 17, 2004
4,219
2,551
136

DrMrLordX

Lifer
Apr 27, 2000
22,475
12,331
136
Galax has a 5090 with dual 12 pin connectors in their lab, it's not clear if they will, or are allowed to ship to customers, but they should. It also appears to have 5 shunt resistors for measuring incoming power:
Why would they not be allowed to ship to customers?
 

Jan Olšan

Senior member
Jan 12, 2017
506
981
136
All partner cards have to get Nvidia approval. The thing that happened is likely that

1) visuals design guys want 1 connector/cable to look slick and they got the upper bosses on board with that idea (against the engineers, possibly).
2) inevitable safety issues
3) you (Founders edition cards) don't want to look bad/usafe next to partner cards that would put two connectors on their stuff to give better safety margins.
4) disallow partners from making 2xcable cards to "solve" problems 2-3.
 

coercitiv

Diamond Member
Jan 24, 2014
7,073
16,281
136
5) creates mayhem among PSU makers, as there most certainly are PSU models out there with a single 12V-2x6 connector that are more than capable of handling the 5090.


The entire marketing pitch for this connector was built around 1x connectivity for anything except extreme builds / overclocking.
 

Jan Olšan

Senior member
Jan 12, 2017
506
981
136
Well, those can still throw the spider adapter from 8pins on a double-cable card. Which is what people started recommending for RTX 5090 anyway when the native cables started melting, ironical given how everyone first got new PSUs with native/straight 12+4 cables...
 
Reactions: igor_kavinski

DrMrLordX

Lifer
Apr 27, 2000
22,475
12,331
136
@Jan Olšan @coercitiv

NV's reference design for the 4090Ti already uses two connectors, though. All they had to do was copy that. The only technical reason I've heard as to why they didn't do that is that some designer or another insisted on limited PCB space for a specific airflow/heatsink topology, leading to the single connector at an odd angle.
 
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