Nvidia's RTX 5090 power connectors are melting

Original Article ↗ Hacker News Discussion ↗

Electrical Limits and Why Connectors Melt

  • Many comments drill into basics: 600 W at 12 V implies ~50 A; the C13-style “wall” connector only works because it’s at 120–240 V (much lower current).
  • Heat is driven by I²R in the cable and especially the contacts. With 12VHPWR/12V‑2x6, each of 6 power pairs should carry ~8.3 A, while typical Micro‑Fit–style contacts are rated ~9.5–10 A – almost no safety margin.
  • Tests cited in the thread show badly unbalanced current: one wire measured ~22 A and >150 °C while others carried very little, suggesting serious distribution issues.

Critique of 12VHPWR / 12V‑2x6 Design

  • Several analyses describe Nvidia’s newer cards shorting all 12 V pins together on a bus bar with a single shunt, so no per‑pin load balancing or meaningful fault detection.
  • By contrast, older multi‑8‑pin designs (and earlier xx90 cards) used multiple shunts and separate wiring paths that naturally equalized current and gave more headroom.
  • Commenters slam the spec for effectively running connectors and 16–18 AWG wiring at or above rated current, calling the design “broken by design” and extremely sensitive to minor seating or manufacturing issues.

Third‑Party Cables vs Nvidia Responsibility

  • Some blame the featured failure on an aftermarket cable and user error (using a 12VHPWR cable with a 12V‑2x6 card).
  • Others counter:
    • GPU‑side ports are intentionally backward‑compatible, so plugging in old‑standard cables is “allowed by design.”
    • All GPU power cables are “third‑party” from either the PSU’s or GPU’s perspective; the connector standard should tolerate realistic variance.
    • There are already multiple 5090 failures, including with manufacturer‑supplied cables, suggesting a systemic margin problem.

Higher Voltage Rails and Alternative Connectors

  • Strong thread arguing 12 V is the wrong choice at kilowatt scale; calls for 24 V or 48 V rails to cut current (and I²R losses) by 2–4×, even if it requires extra DC‑DC stages on the card.
  • Others note real obstacles: ATX ecosystem inertia, regulation around “safe” extra‑low voltage, cost/complexity of 48→1 V conversion, and need for industry‑wide PSU changes.
  • Proposed alternatives: multiple independent connectors, screw‑in or ring‑lug terminals, high‑current RC/XT‑style plugs, external “brick” PSUs or even separate mains cords for GPUs.

General PC Connector Frustration and Cost Pressures

  • Many vent about internal PC connectors being hard to seat, fragile, and unergonomic compared to USB/HDMI, despite multi‑thousand‑dollar parts hanging off them.
  • Some engineers explain why good connectors are genuinely hard and expensive: precise crimps, retention, contact geometry, compactness, long life, backwards compatibility, and unit‑cost targets measured in cents.
  • Others respond that, on a $2,000+ flagship GPU with huge margins, shaving a dollar or two on power connectors is unjustifiable.

Power Consumption and Product Strategy

  • Discussion questions why consumer GPUs need 500–600 W at all, comparing this to “space heaters for games and boilerplate AI.”
  • Counterpoint: the halo tier is explicitly “as fast as physics, cost and power allow”; demand for 4K/RT/high‑FPS and AI means the market rewards absolute performance more than efficiency at the top end.
  • Some users state they are choosing AMD cards or skipping upgrades entirely over both price and power/connector concerns.

Safety, Regulation, and Liability

  • Questions raised about possible breaches of safety norms when running near or above connector/wire ratings; suggestions that CE or product‑liability regulators might eventually step in.
  • Others note UL is private and enforcement is mainly via market and insurance, not criminal law; nonetheless, repeated melting incidents are seen as a serious reputational and risk issue.