Why Samsung's US Galaxy S III has a dual-core processor (and why you shouldn't ...

In just a couple of weeks, the U.S. will receive its first Samsung Galaxy S III smartphones. The flagship phones share most of the features of the global version of the device -- Android 4.0 Ice Cream Sandwich and a huge 4.8-inch HD Super AMOLED display, to name but two -- but the U.S. variant differs on three points: LTE capability, 2GB RAM (versus 1GB in the global version), and a dual-core processor instead of a quad-core processor.

It's this last spec that tends to get people in a tizzy, despite the fact that quad-core processors aren't necessarily faster or more efficient than dual-core CPUs.

In fact, CNET and other tech outlets have found Qualcomm's Snapdragon S4 chipset more than capable in the HTC One X and HTC One S phones, which were also the first to debut with Qualcomm's fastest-yet system-on-a-chip.

There's a good reason that Samsung and HTC both chose Qualcomm's Snapdragon S4 processor for their flagship handsets, instead of the quad-core processors introduced in the global version of the devices (Nvidia's Tegra 3 processor, in HTC's case.) And that reason more or less boils down to LTE.

In the case of the Galaxy S III, the short, simplified answer is that Snapdragon S4 is a complete chipset that bundles the application processor, cellular radios, and LTE radio into a fast package that's ready now.

The slightly longer answer is that Samsung's Exynos 4 quad-core processor is an application processor only, and does not bundle the requisite radios for America's LTE networks.

Nick DiCarlo, vice president of product planning for Samsung's mobile division, told CNET, "Carriers using LTE all have different network requirements, due to different frequency bands, as well as different 3G networks" -- like CDMA and GSM technologies.

It's very common to group a standalone application processor like the Exynos 4 Quad with the necessary radios to meet a market's LTE network requirement -- that was Samsung's strategy with the U.S. version of the Galaxy Nexus, in fact, using a Texas Instruments OMAP processor.

However, the U.S. version of the Galaxy Nexus is also slightly thicker to accommodate the extra components. Depending on how the manufacturer sources the various processors and radios, it may need to make certain trade-offs in terms of battery size, physical design, or the product's release schedule.

In addition, LTE chip add-ons also add cost, and can impact battery life.

Samsung's DiCarlo explained that opting for Snapdragon S4 inside gives the Galaxy S III LTE, GSM/CDMA, and a CPU in one manageable unit -- while still hitting a summer release date for all five U.S. carrier partners.

"There are 150-plus designs in development using S4," Tim McDonough, vice president of marketing for Qualcomm CDMA Technologies, has told CNET. "Most of those are with two cores and integrated LTE because there are huge benefits to having LTE built in."

DiCarlo also stressed Samsung's confidence in the Galaxy S III's performance speeds with Qualcomm's chip. Based on the performance of the HTC One X and One S, we're expecting good things. CNET will keep a close eye on overall speeds when we review the Samsung Galaxy S III variants.

In the meantime, you can check out my hands-on take on the global version of the Samsung Galaxy S III, or CNET UK's full review.