Asus Zenfone 3 review

Performance

The Asus Zenfone 3 ZE552KL is powered by Qualcomm's Snapdragon 625 chipset - a mid-range chipset built on the power efficient 14nm process. For comparison, the Snapdragon 650 and 652 are built on the older 28nm process, but they do have big Cortex-A72 cores and a more powerful GPU (the S625 uses only Cortex-A53 cores, eight of them).

We already have some experience with this chipset - both the Huawei nova plus (5.5" 1080p screen) and Samsung Galaxy C7 (5.7" 1080p) use it. They cost about the same as the Zenfone 3 as well, that is to say more than typical mid-range Android and as much as some of the best 5.5" phones in the biz.

Eight Cortex-A53 cores at a high 2GHz clock speed make for great multi-threaded performance, as fast as the Snapdragon 820 in the OnePlus 3 and slightly behind the Helio X20 chip in the Xiaomi Redmi Note 4 (X20 has eight A53 cores, but also a couple of A72 cores).

GeekBench 4 (multi-core)

Higher is better

• Xiaomi Redmi Note 4
  4456
• Asus Zenfone 3 ZE552KL
  4053
• OnePlus 3
  4045
• ZTE Axon 7
  3990
• Huawei nova plus
  3100

Still, without a big A72 core single-threaded performance is less than impressive. You can see both the Kryo (Snapdragon 820) and Cortex-A72 (Helio X20) cores easily outpace it. Meanwhile even the Moto G4 Plus, which uses an old Snapdragon 617 chipset (A53 cores at just 1.5GHz), isn't that far behind.

GeekBench 4 (single-core)

Higher is better

• OnePlus 3
  1719
• ZTE Axon 7
  1702
• Xiaomi Redmi Note 4
  1546
• Huawei nova plus
  843
• Asus Zenfone 3 ZE552KL
  843

In terms of overall performance, the Asus Zenfone 3 ZE552KL is closer to the Moto G4 Plus than it is to the OnePlus 3, ZTE Axon 7 and other value for money entries in the 5.5" segment. Of course, those don't quite have the brand recognition of Asus, but there's no escaping that better chipsets exist in this price segment.

AnTuTu 6

Higher is better

• OnePlus 3
  141764
• ZTE Axon 7
  129926
• Xiaomi Redmi Note 4
  85162
• Huawei nova plus
  64680
• Samsung Galaxy A9 (S652)
  64591
• Asus Zenfone 3 ZE552KL
  63358
• Samsung Galaxy C7
  62818

Moving to 3D graphics, the Adreno 506 inside the Snapdragon 625 just isn't that impressive. It beats the aging Adreno 405 inside the Moto G4 Plus by some margin (especially if the game engine uses an older version of OpenGL ES - 3.0 instead of 3.1).

However, it's no match for the Adreno 510 used in the Snapdragon 650 and 652 chips that power, for example, the older Redmi Note 3. That matches the GPU inside the new Redmi Note 4, but all of those are far from a flagship GPU as the OnePlus and Axon demonstrate.

GFX 3.0 Manhattan (1080p offscreen)

Higher is better

• OnePlus 3
  46
• ZTE Axon 7
  15
• Xiaomi Redmi Note 4
  15
• Samsung Galaxy A9 (S652)
  13
• Huawei nova plus
  9.9
• Asus Zenfone 3 ZE552KL
  9.9
• Samsung Galaxy C7
  9.8

GFX 3.1 Car scene (offscreen)

Higher is better

• OnePlus 3
  18
• ZTE Axon 7
  15
• Xiaomi Redmi Note 4
  5.4
• Huawei nova plus
  3.4
• Samsung Galaxy C7
  3.4
• Asus Zenfone 3 ZE552KL
  3.4

The Asus Zenfone 3 ZE552KL is helped by its screen resolution - 1080p. You can see that even the top end Adreno struggles with the QHD resolution on the Axon 7 and its QHD screen. The gap in on-screen results is much smaller and we think on-screen results are more important (though some games render at a lower resolution internally, i.e. games on the Axon 7 don't have to run at QHD).

GFX 3.0 Manhattan (onscreen)

Higher is better

• OnePlus 3
  45
• Xiaomi Redmi Note 4
  15
• Samsung Galaxy A9 (S652)
  13
• ZTE Axon 7
  12
• Huawei nova plus
  10
• Asus Zenfone 3 ZE552KL
  9.7
• Samsung Galaxy C7
  9.6

GFX 3.1 Car scene (onscreen)

Higher is better

• OnePlus 3
  18
• ZTE Axon 7
  16
• Xiaomi Redmi Note 4
  5.4
• Huawei nova plus
  3.7
• Samsung Galaxy C7
  3.4
• Asus Zenfone 3 ZE552KL
  3.4

The Snapdragon 625 chipset is found on some very similar phones - the Zenfone 3, nova plus and Galaxy C7 have a lot in common, including price. The chip provides adequate performance, especially with a 1080p screen, but there are better options out there at a similar price.

We do have to note that the phone runs very cool - even after half an hour of hard-hitting benchmarks it got only slightly warm.