In the world of DIY PC, it’s bad enough whenever we hear stories of 12VHPWR PCIe cables melting and burning, with the latter nearly taking an entire house down with it. Today’s cautionary tale, however, isn’t about using the provided cables: it’s about not taking a single 8-pin PCIe power cable and splitting it into a dual 8-pin PCIe power connector.
Our story takes us to Russia and more specifically, the YouTube channel of Russian TechTuber VIK-off, who shows off a system powered by an NVIDIA RTX 5070 and, if it wasn’t already made obvious in the title, a melted PCIe cable. The story is a twofer, literally: the card was powered by a 12VHPWR adapter, with the dual 8-pin PCIe power headers on the other end. Nothing out of the ordinary here.
The second part of this build was how the dual 8-pin headers were connected: a single, separate 8-pin PCIe power cable, split into two. This, in itself, was a disaster waiting to happen.
Two Become One, Not The Other Way Round
In broad strokes, one 8-pin PCIe connector is capable of running up to 150W of power, with a dual 8-pin PCIe connector handling double that, and directly from the PSU. The 12VHPWR Gen 5 connector, which was first introduced with the launch of the NVIDIA RTX 40 Series GPU in 2022, is designed to handle up to 600W in a single throughput, significantly more than the standard 8-pin. The RTX 5070 itself requires up to 250W TGP, with a recommended 650W PSU for good measure.
At a very rudimentary level of electrical engineering, even this writer knows that you should never, ever split a single 8-pin PCIe cable into two. Doing this does not double the output, nor does it create another power source. Ultimately, RTX 5070 was essentially duped into pulling more power through the cable than it was able to handle, which resulted in the melted casualty that you see in the video (It starts at the 11:58 mark). To that end, even NVIDIA says that you should use two separate 8-pin cables to power the card.
By some dark miracle, the 12VHPWR end survived, as did the card from the looks of it. To be clear, there are 8-pin splitter cables, but these typically split into dual 6-pin headers, designed for lower power GPUs, and they channel the 150W when used together. This, though? This was the owner literally playing with fire.
(Source: VIK-off via YouTube, Videocardz)
