All it takes is a €50 mod to keep this AMD GPU chill and in complete silence

There's an entire niche of our hobby dedicated to building quiet, if not silent, PCs. I absolutely love it. It's not just that these parts are passively cooled and require no moving parts, it's also how properly awesome they all look. 

Take this passively cooled AMD Radeon RX 6400 graphics card from Reddit user Revoccases (spotted by our pals at FanlessTech), it's gorgeous. It's also massively oversized, as you might have noticed, and the actual GPU is hidden by a heatsink loosely three times its size. But it's all in the name of silent operation and thermal performance.

This card is a humble RX 6400, which comes with just 12 Compute Units for a total of 768 shader cores. As such, it's not a wildly powerful gaming GPU, but you'd be very hard pressed to keep an RTX 4090 cool without any fans whatsoever. Let's be real, for this sort of passive mod we're looking at something more moderate, and with a typical board power of 53W, and the RX 6400 is just that.

Revoccases goes through all the steps required to build out this mod over on the smallformfactor.net forum. First they started with a low profile card and then machined out a 3mm copper coldplate to cover the GPU and memory. The GPU and memory are at slightly different heights, so there are some thermal pads required to get proper contact.

The actual heatsink part is the Accelero S1, a sink and heat pipe cooler that's been around for a decade and a half, which is then soldered onto the coldplate.

The result is a card that, during a one-hour stress test in the Heaven benchmark, reached just 60°C via the hotspot reading on the card, and only 54°C from the GPU temp sensor.

Revoccases told me that the entire mod cost around €50, though you'd need to add the cost of the RX 6400 to that if you intend to mod that exact card yourself. Thankfully, they've also uploaded drawings of the coldplate over on the forum post for all to use.

The whole build is nicknamed the Kalmx AMD Edition, a nod to one of the very few truly passive graphics cards in recent years, the Palit GeForce RTX 1650 KalmX. They just don't make many like it anymore, despite there being a couple of cards suitable, as Revoccases tells me.

"The RX 6400 and [RTX] A2000 are perfect for passive cooling but it seems too much of a niche these days for manufacturers to offer something like the KalmX to end customers."

It's a shame, but this project just goes to show you don't necessarily need a manufacturer to do the work for you. But you will need to be at least a little bit handy machining metals, or know someone who is.

Now to pair one of these passive GPUs with Noctua's NH-P1... it won't be powerful, but it will be perfectly silent.