New PC power supply unit to monitor currents on 12V 2x6 connection

At the Computex trade fair in Taiwan this week, Seasonic showed the prototype of a power supply unit in which the currents on the individual 12-volt lines of the controversial 12V-2x6 connector are monitored. The design formerly known as 12VHPWR has only been slightly revised with its new name and still does not provide for any monitoring of the currents and voltages; the small sense pins only report whether the current-carrying lines are connected.

There have been isolated reports of melting connectors on 12VHPWR or 12V-2x6 for years, and this became particularly explosive with Nvidia's Geforce RTX 5090. With a TDP of 575 watts, it is close to the maximum of 600 watts for which the connection is specified. The situation is exacerbated by the fact that Nvidia's reference design provides for the 12-volt lines on the graphics card to be combined without any protective mechanisms. If one of the lines has an increased internal resistance, for example due to wear or soiling of the connectors, the others compensate for the current. This does not necessarily mean, as hardware manufacturers often claim, that there is incorrect operation due to connectors not being fully inserted.

These cables and the plugs can then become so hot that the plugs can melt into the sockets on the power supply unit and the graphics card, and there is also a risk of fire. There is already a verifiable report from a user where this happened at both ends of the cable with an RTX 4090. Some manufacturers help themselves by monitoring the currents on the graphics card using shunt resistors, the voltage drop of which can be used to measure the current. This is the case with the Astral graphics cards with RTX 5090 from Asus and the Sapphire Nitro+ 9070XT, for example.

Too much current? Power supply switches off

Seasonic now wants to tackle the problem on the power supply side, as reported by YouTube channels der8auer and Gamers Nexus, among others. In his video, hardware developer Roman "der8auer" Hartung also shows in some detail the prototype of a Seasonic power supply from the Prime TX-1600 series, i.e. with 1600 watts. According to his description, the 12-volt lines of the two 12V 2x6 sockets can all be monitored via shunt resistors. If an as yet undisclosed limit value is exceeded, the power supply unit should switch off. It is expected to be launched on the market in early 2026 at the earliest.

According to Hartung, Seasonic has not yet decided on a possible warning mechanism: the user should know what caused the system to switch off spontaneously. A speaker in the power supply unit would be conceivable here, or perhaps a USB connection from the power supply unit to the mainboard, including the corresponding software. The power supply shutdown can also be triggered by other protective mechanisms on the mainboard or even the processor. For his solution, the Wireview Pro II monitoring module on the graphics card, also still at the prototype stage, Hartung has opted for a loudspeaker.

With all these designs, however, the hardware manufacturers are obviously running into the problem that the standards for 12V-2x6 and PCIe 5.0 do not provide any monitoring or warning mechanisms for the potentially too hot plug connections. Or, seen the other way around: That the connectors have been designed with such low safety reserves that such measures are necessary at all.

(nie)