In a move that will shock and disgust bleeding-edge technophiles everywhere, Asus has announced at Mobile World Congress 2012 that its new Transformer Pads — the high-end Infinity Series — will use the recently-announced dual-core Qualcomm S4 SoC. The critically acclaimed Transformer Prime, the Infinity Series’ predecessor which was released at the end of 2011, used the quad-core Nvidia Tegra 3.

At first blush this looks like a major blow to quad-core processors in general and Nvidia in specific. Almost the entirety of Nidia’s Tegra 3 marketing campaign has revolved around the fact that it’s the first commercially available quad-core part. Asus with the Transformer Prime (the first quad-core tablet), and more recently LG with the Optimus 4X (the first quad-core smartphone), have been at pains to point out the awesomeness of quad-core mobile computing. Now, just a few months after the Prime’s release and before the 4X’s public release, we have Asus disavowing four cores in favor of two.

Why the about-face, then? There are at least three compelling reasons. First, Tegra 3 uses fairly standard Cortex-A9 cores; the S4 uses Qualcomm’s very own Krait cores, which might even be faster than the upcoming Cortex-A15. For comparison, ARM has said that, at the same clock speed, A15 will be 40% faster than the A9. In other words, Tegra 3 is based on technology that is at least one generation behind the S4. It might have more cores, but as we all know, that doesn’t directly translate into more processing power. AMD and Intel have been pushing multi-core chips for seven years now, and yet computing is still predominantly single-threaded. There are a few compelling use cases for dual-core chips, but almost none for quad-core.

The second advantage that the S4 has over Tegra 3 is die size. The Qualcomm S4 will be the first 28nm SoC, while the Tegra 3 (and every other competitor) is still at 40nm. This will mean that the S4 is both smaller and cheaper than Tegra 3, and yet also consumes less power. You could argue that Tegra 3’s Companion Core reduces the gap in power consumption, but Qualcomm’s method of dynamically scaling CPU frequency seems to be just as effective, if not more so.

Finally, the S4 is the first SoC to feature an integrated second-generation LTE radio — which is even more exciting when you remember that it’s the first 28nm LTE radio, too.

In short, then, Asus chose the S4 because it’s superior to Tegra 3 in almost every way. Tegra 3 will still have the edge on graphics performance, thanks to its juicy GPU — but then again, just this morning Qualcomm announced at MWC that an S4 Pro is coming in the second half of 2012. The Pro will be identical to the MSM8960, but instead of yesteryear’s Adreno 225 GPU it will have the Adreno 320, which should kick all sorts of ass.

Updated: The WiFi model of the Asus Transformer will still use the Tegra 3 SoC. We’re not entirely sure why this is the case — supporting multiple SoCs is unnecessarily complicated — but presumably Asus has good reason to do so.