The Importance Of Current Balancing With Multi-Wire Power Inputs

February 24, 2025 by 87 Comments

In an ideal world, devoid of pesky details like contact resistance and manufacturing imperfections, you would be able to double the current that can be provided to a device by doubling the number of conductors without altering the device’s circuitry, as each conductor would carry the exact same amount of current as its neighbors. Since we do not actually live inside a simplified physics question’s scenario, multi-wire powering of devices comes with a range of headaches, succinctly summarized in the well-known rule that electricity always seeks the path of least resistance.

As recently shown by NVidia with their newly released RTX 50-series graphics cards, failure to provide current balancing between said different conductors will quickly turn it into a practical physics demonstration of this rule. Initially pinned down as an issue with the new-ish 12VHPWR connector that was supposed to replace the 6-pin and 8-pin PCIe power connectors, it turns out that a lack of current balancing is plaguing NVidia GPUs, with predictably melty results when combined with low safety margins.

So what exactly changed that caused what seems to be a new problem, and why do you want multi-wire, multi-phase current balancing in your life when pumping hundreds of watts through copper wiring inside your PC?

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Where No E. Coli Has Gone Before

February 24, 2025 by 11 Comments

While we’re still waiting for ET to give us a ring, many worlds might not have life that’s discovered the joys of radio yet. Scientists ran a two-pronged study to see how bacteria might fare on other worlds.

We currently define the Habitable Zone (HZ) of a planet by the likelihood that particular planet can host liquid water due to its peculiar blend of atmosphere and distance from its star. While this doesn’t guarantee the presence of life, its a good first place to start. Trying to expand on this, the scientists used a climate model to refine the boundaries of the HZ for atmosphere’s dominated by H2 and CO2 gases.

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Unhacked Mattress Phones Home

February 24, 2025 by 30 Comments

[Dylan] has a fancy bed that can be set to any temperature. Apparently this set him back about $2,000, it only works if it has Internet, and the bed wants $19 a month for anything beyond basic features. Unsurprisingly, [Dylan] decided to try to hack the mattress firmware and share what he learned with us.

Oddly enough, it was easy to just ask the update URL for the firmware and download it. Inside, it turned out there was a mechanism for “eng@eightsleep.com” to remotely SSH into any bed and — well — do just about anything. You may wonder why anyone wants to gain control of your bed. But if you are on the network, this could be a perfect place to launch an attack on the network and beyond.

Of course, they can also figure out when you sleep, if you sleep alone or not, and, of course, when no one is in the bed. But if those things bother you, maybe don’t get an Internet-connected bed.

Oddly enough, the last time we saw a bed hack, it was from [Dillan], not [Dylan]. Just because you don’t want Big Sleep to know when you are in bed doesn’t mean it isn’t useful for your private purposes.

Does The 12VHPWR Connector Really Wear Out After 30 Mating Cycles?

February 23, 2025 by 50 Comments

When PCI-SIG introduced the 12VHPWR power connector as a replacement for the 6- and 8-pin PCIe power connectors, it created a wave of controversy. There were enough cases of melting GPUs, PSUs, and cables to set people on edge. Amidst this controversy, [JayzTwoCents] decided to do some scientific experimentation, Mythbusters-style, specifically: do these 12VHPWR (or the 12V-2×6 successor) wear out upon hitting the often cited 30 mating cycles? If this is the case, it could explain why people see wildly different current loads between the wires in their GPU power cables. Perhaps reviewers and hardware enthusiasts should replace their  GPU power cables more often.

Like many Mythbuster experiments, the outcome is less than clear, as can be observed in the below graph from one data set. Even after 100 mating cycles, there was no observable change to the contact resistance. One caveat: this was only performed on the GPU side of the connector. The first cable tested was a newer connector type that uses a single-split leaf spring design. Initially, most of the 12VHPWR connectors had a double- or triple-dimple design to contact the pin, so [Jayz] tested one of these, too.

The amazing thing with the 2022-era cable that got pulled new out of packaging and tested was that it looked terrible under the microscope in terms of tolerances and provided a very uneven load, but it got better over time and also lasted 100 cycles. However, it must be said that ‘lasted’ is a big word here, as the retention tab wore off by this point, and the connector was ready to fall out with a light breeze.

Perhaps the ‘mating cycles’ specification is more about the connector as a whole, as well as how the connector is (ab)used, at which point good (long-term) contact is no longer assured. Along with the different types of Molex Mini- and Micro-Fit style connectors, it’s worth keeping an eye on with more applications than just GPUs.

We have certainly seen some burned connectors. Particularly in 3D printers.

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Learn Assembly The FFmpeg Way

February 23, 2025 by 26 Comments

You want to learn assembly language. After all, understanding assembly unlocks the ability to understand what compilers are doing and it is especially important for time-critical code. But most tutorials are — well — boring. So you can print “Hello World” super fast. Who cares?

But decoding video data is something where assembly can really pay off, so why not study a real project like FFmpeg to see how they do things? Sounds like a pain, but thanks to the FFmpeg asm-lessons repository, it’s actually quite accessible.

According to the repo, you should already understand C — especially C pointers. They also expect you to understand some basic mathematics. Most of the FFmpeg code that uses assembly uses the single instruction multiple data (SIMD) opcodes. This allows you to do something like “add 5 to these 200 data items” very quickly compared to looping 200 times.

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Hackaday Links: February 23, 2025

February 23, 2025 by 7 Comments

Ho-hum — another week, another high-profile bricking. In a move anyone could see coming, Humane has announced that their pricey AI Pin widgets will cease to work in any meaningful way as of noon on February 28. The company made a splash when it launched its wearable assistant in April of 2024, and from an engineering point of view, it was pretty cool. Meant to be worn on one’s shirt, it had a little bit of a Star Trek: The Next Generation comm badge vibe as the primary UI was accessed through tapping the front of the thing. It also had a display that projected information onto your hand, plus the usual array of sensors and cameras which no doubt provided a rich stream of user data. Somehow, though, Humane wasn’t able to make the numbers work out, and as a result they’ll be shutting down their servers at the end of the month, with refunds offered only to users who bought their AI Pins in the last 90 days.

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Over The Counter Glucose Monitor Dissected

February 23, 2025 by 37 Comments

If you deal with diabetes, you probably know how to prick your finger and use a little meter to read your glucose levels. The meters get better and better which mostly means they take less blood, so you don’t have to lacerate your finger so severely. Even so, taking your blood several times a day is hard on your fingertips. Continuous monitoring is available, but — until recently — required a prescription and was fairly expensive. [Andy] noticed the recent introduction of a relatively inexpensive over-the-counter sensor, the Stelo CGM. Of course, he had to find out what was inside, and thanks to him, you can see it, too.

If you haven’t used a continuous glucose monitor (CGM), there is still a prick involved, but it is once every two weeks or so and occurs in the back of your arm. A spring drives a needle into your flesh and retracts. However, it leaves behind a little catheter. The other end of the catheter is in an adhesive-backed module that stays put. It sounds a little uncomfortable, but normally, it is hardly noticeable, and even if it is, it is much better than sticking your finger repeatedly to draw out a bunch of blood.

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