Samsung Galaxy Note 4 and Nexus 6 (Snapdragon 805) performance review

It has been a long stay at the top for Qualcomm. 

The company introduced its first Krait CPU core way back in 2012, and ever since then the Krait core has been the brain of most of the successful Android and Windows Phone devices. A custom creation, Qualcomm designed the Krait core under ARM’s architecture license, meaning that it only used the very basics that ARM provided like the instruction set, while for all else it was Qualcomm engineers who were charged with the task to carefully tweak performance to come with an efficient and powerful core.

This year, with the Samsung Galaxy Note 4 and the Nexus 6, both equipped with the latest Snapdragon 805 featuring a refined Krait core, we’re seeing the swan song of this three-year old CPU design: the Krait 450.

Krait 450: the swan song for 32-bit

The latest big jump in performance for the Krait family of processors happened with the release of the Snapdragon 800, also known as the MSM8794, a chip that appeared on devices like the Samsung Galaxy Note 3, Nexus 5, and Sony Xperia Z1 in 2013. The Snapdragon 800 debuted the Krait 400 core (a very similar Krait 400 CPU core was later used in the Snapdragon 801), that in turn brought the increase in clock speeds - from about 1.7GHz in the previous generation Krait cores to 2.3GHz on the Krait 400. The main reason for this substantial boost in clock speed was the change in the manufacturing process. While earlier Snapdragon chips were made on the 28nm LP (low-power) node, the Krait 400 was the first to be made on a 28nm HPm (high-performance for mobile) node. At the same time, it’s worth keeping in mind that Qualcomm did not make any huge changes in the underlying Krait core architecture, leaving instruction parallelism on the same level.

This was a short run through the facts that lead us to the Krait 450 design. It’s important to remember all those things when speaking about the Krait 450 as it is a gradual build-up from the Krait 400 core.

The particular implementations of the Krait 450 on the Samsung Galaxy Note 4 and Nexus 6 run at up to 2.65GHz. We’re looking at the same 3-wide decode, 4-issue with 7 execution ports and 11-level deep pipeline architecture as in previous Krait cores. On board is also a 32KB of L1 cache (16KB Instruction $ and 16KB Data $), as well as 2MB of shared L2 cache.


All of this follows the ARMv7 instruction set. It’s worth pointing out that Snapdragon 805 is the last 32-bit high-end Qualcomm architecture, and as such it has a special place, as many tech geeks might be willing to wait a bit for the 64-bit ARMv8 implementations in Snapdragon 810. That forthcoming chip will also no longer use custom Qualcomm cores - instead, it will just use a Cortex A5x (A57/A53) setup.

As to the performance delta between the new Krait 450 and Krait 400, we look at a number of CPU benchmarks, starting with Geekbench. Geekbench runs a few low-level tests for integer and floating point performance, and it measures both single-core and multi-core performance, with a unified score that is easy to use as a quick comparison between processors.

The Krait 450 scores an average of around 1100 points on the single-core Geekbench test. We ought to point out that the single-core performance score is essential and arguably correlates best with real-life performance. The reason is that the use of multiple cores is a territory usually reserved for more demanding applications, and even though Android offers an excellent support for relating the load between cores, single-core performance is still critical. So how much of an improvement is the 1100-ish score of the Galaxy Note 4 and Nexus 6? Compared to a Krait 400 device like, say, the LG G2, which scores around 930. Keep in mind that there is a slight fluctuation in the scores because of the little variables that affect CPU performance in the daily grind. Still, a jump from a score of around 930 to 1100 is an improvement in the ballpark of a solid 18%.


Looking over to multi-core performance, the Krait 450-based Galaxy Note 4 and Nexus 6 score around 3270 points on Geekbench, while the Krait 400-running LG G2 averages 2750. Here, the improvement also measures to around 19%, which is - logically - consistent with the boost we saw in single-core performance. After all, both the Snapdragon 805 and the Snapdragon 800 use a quad-core setup.