Asus Zenfone 2 review: A balancing act

Intel inside

The entire Zenfone 2 range is powered by Intel Atom chipsets, and the ZE551ML we have at the office has an Atom Z3560 SoC with its quad-core processor clocked anywhere between 500MHz and 1.83GHz, depending on the work load.

Update, June 11: We have added the benchmark scores of the range-topping Asus ZenFone 2 with 4GB of RAM. In addition to more memory, it packs a more powerful Intel Atom Z3580 SoC with 2.3 GHz quad-core CPU. For comparison, Asus ZenFone 2 with 2GB of RAM features Intel Atom Z3560 with 1.8GHz quad-core CPU.

The 4GB Asus ZenFone 2 delivered mostly impressive performance across the board, leaving many flagship devices behind it on more than one occasion. As expected, the 4GB variant is also noticeably faster than its sibling with 2GB of RAM.

Intel's offerings can hardly impress with numbers in the Android realm, where higher-clocked octa-core processors have become the norm. However, the Atom Z3560 proved to be able to compete with the Snapdragon 800 and its quad-core 2.26GHz processor, back when we reviewed the Asus Memo Pad ME572C, a similarly specced tablet.

Our review unit comes with 2GB of RAM, which should be about enough for smooth daily usage. Demanding power users, who do a lot of multitasking may choose to go with the top model that comes with 4GB and the faster Atom Z3580, albeit at a price premium.

We tried to pick a few of the Zenfone 2's market rivals, which are frankly hard to pinpoint, but also threw in the current crop of flagships to see how it compares to the leading performers out there.

We'll start with the CPU centric Geekbench 3.0 test. As expected, the Zenfone 2 doesn't impress with raw CPU performance and is miles behind the 1.7GHz octa-core Meizu m1 note. The Samsung Galaxy Note 3 with S800 together with the Oppo Find 7a and OnePlus One both powered by S801 are ahead as well. Still, the Zenfone 2 manages to inch ahead of both LG G2 and G3 and is superior to the Galaxy Note 3 Neo.

GeekBench 3

Higher is better

• Samsung Galaxy S6
  5215
• Meizu m1 note
  3988
• HTC One M9
  3761
• LG G Flex2
  3604
• Meizu MX4
  3556
• Samsung Galaxy Note 4 Lollipop
  3394
• Xiaomi Mi Note
  3094
• Oppo Find 7a
  3093
• Samsung Galaxy Note 3 S800
  2937
• Asus ZenFone 2 ZE551ML (4GB of RAM)
  2922
• Samsung Galaxy A7 (S615)
  2880
• OnePlus One
  2663
• LG G Pro 2
  2585
• Xiaomi Redmi Note
  2435
• Asus Zenfone 2 ZE551ML
  2423
• LG G3
  2370
• LG G2
  2243
• Samsung Galaxy Note 3 Neo
  2172
• HTC Desire 816
  1510

Antutu 5 adds RAM and storage speed into the mix and is an indication of the overall performance of the device. The Zenfone 2 delivers a strong performance, on par with the Galaxy Note 3 with S800 and the LG G3 with S801.

AnTuTu 5

Higher is better

• Samsung Galaxy S6
  69396
• HTC One M9
  51427
• Samsung Galaxy Note 4 Lollipop
  49273
• Asus ZenFone 2 ZE551ML (4GB of RAM)
  48361
• LG G Flex2
  47680
• Meizu MX4
  46922
• Xiaomi Mi Note
  45632
• Asus Zenfone 2 ZE551ML
  42301
• Samsung Galaxy Note 3 S800
  42211
• LG G3
  42038
• Meizu m1 note
  39224
• Xiaomi Redmi Note
  32487
• Samsung Galaxy A7 (S615)
  31436

The even broader Basemark OS II benchmark continues the trend. Overall, the Zenfone 2 performs well, if far from the top of the current flagship crop. Again, the Galaxy Note 3 and G2 remain behind.

As expected though, the CPU focused parts of the benchmark weren't the Atom's strong suit and it was bolted to bottom of the comparison charts.

Basemark OS II

Higher is better

• Samsung Galaxy S6
  1769
• LG G Flex2
  1601
• HTC One M9
  1526
• Xiaomi Mi Note
  1370
• Samsung Galaxy Note 4 Lollipop
  1332
• LG G3
  1327
• Asus ZenFone 2 ZE551ML (4GB of RAM)
  1267
• OnePlus One
  1196
• LG G Pro 2
  1140
• Asus Zenfone 2 ZE551ML
  1094
• Oppo Find 7a
  1057
• Samsung Galaxy Note 3 S800
  1003
• LG G2
  848
• Samsung Galaxy A7 (S615)
  786
• Meizu m1 note
  715
• Meizu MX4
  695
• HTC Desire 816
  520
• Xiaomi Redmi Note
  452

Basemark OS II (single-core)

Higher is better

• Samsung Galaxy S6
  3497
• Oppo Find 7a
  2580
• Samsung Galaxy Note 4 Lollipop
  2574
• Xiaomi Mi Note
  2559
• LG G Flex2
  2528
• HTC One M9
  2401
• LG G Pro 2
  2401
• LG G3
  2267
• Samsung Galaxy Note 3 S800
  2236
• OnePlus One
  2213
• Asus ZenFone 2 ZE551ML (4GB of RAM)
  1853
• Meizu m1 note
  1754
• HTC Desire 816
  1739
• Meizu MX4
  1729
• Xiaomi Redmi Note
  1701
• Samsung Galaxy A7 (S615)
  1572
• Asus Zenfone 2 ZE551ML
  1462

Basemark OS II (multi-core)

Higher is better

• Samsung Galaxy S6
  16986
• Meizu m1 note
  12848
• Xiaomi Redmi Note
  12771
• Meizu MX4
  12268
• Oppo Find 7a
  10256
• OnePlus One
  10234
• HTC One M9
  10128
• LG G3
  9975
• LG G Pro 2
  9802
• LG G Flex2
  9758
• Xiaomi Mi Note
  9590
• Samsung Galaxy Note 3 S800
  9364
• Samsung Galaxy A7 (S615)
  9284
• Samsung Galaxy Note 4 Lollipop
  9198
• HTC Desire 816
  7071
• Asus ZenFone 2 ZE551ML (4GB of RAM)
  7002
• Asus Zenfone 2 ZE551ML
  5600

In the graphics department, the Zenfone 2 is equipped with a PowerVR G6430 GPU as Intel doesn't make its own graphics chips for the Atoms. It's a somewhat old GPU, released back in Q3 2013, made by British semiconductor manufacturer Imagination Technologies. It was featured in Apple's A7 SoC inside the iPhone 5S, and is chosen by Intel for the entire range of Z35xx Atoms.

GFXBench returned the same results in both the off-screen and on-screen routines, not exactly surprising, having in mind that the standardized off-screen tests are carried out at 1080p resolution, the same as the actual one on the Zenfone 2.

The GPU puts out solid numbers in the T-Rex test beating the Galaxy Note 3 and the LG G3 and G2. Even the Galaxy Note 4 is a frame behind in the on-screen test, but don't forget its QHD resolution. The more intense Manhattan routine halves the framerate but even so the Zenfone 2 posts great results. Apart from the Galaxy S6 and the Snapdragon 810s, no one proves to be a match.

GFX 2.7 T-Rex (1080p offscreen)

Higher is better

• Samsung Galaxy S6
  59
• HTC One M9
  49
• LG G Flex2
  49
• Samsung Galaxy Note 4 Lollipop
  40
• Asus ZenFone 2 ZE551ML (4GB of RAM)
  30
• Oppo Find 7a
  28.4
• OnePlus One
  28.3
• Xiaomi Mi Note
  28
• Asus Zenfone 2 ZE551ML
  27
• Samsung Galaxy Note 3 S800
  26.3
• LG G3
  26
• LG G Pro 2
  22.9
• Meizu MX4
  22.7
• LG G2
  22
• Samsung Galaxy A7 (S615)
  15
• Meizu m1 note
  15
• Samsung Galaxy Note 3 Neo
  15
• Xiaomi Redmi Note
  9.8
• HTC Desire 816
  5.9

GFX 2.7 T-Rex (onscreen)

Higher is better

• HTC One M9
  50
• LG G Flex2
  48
• Samsung Galaxy S6
  38
• Asus ZenFone 2 ZE551ML (4GB of RAM)
  30
• OnePlus One
  30
• Oppo Find 7a
  28.8
• Xiaomi Mi Note
  28
• Asus Zenfone 2 ZE551ML
  27
• Samsung Galaxy Note 3 S800
  26.7
• Samsung Galaxy Note 4 Lollipop
  26
• Samsung Galaxy Note 3 Neo
  25
• LG G Pro 2
  24.1
• LG G2
  23.1
• Meizu MX4
  21.3
• LG G3
  20
• Meizu m1 note
  16
• Samsung Galaxy A7 (S615)
  15
• Xiaomi Redmi Note
  13.3
• HTC Desire 816
  11

GFX 3.0 Manhattan (1080p offscreen)

Higher is better

• Samsung Galaxy S6
  24
• HTC One M9
  23
• LG G Flex2
  22
• Samsung Galaxy Note 4 Lollipop
  18
• Asus ZenFone 2 ZE551ML (4GB of RAM)
  13
• Asus Zenfone 2 ZE551ML
  13
• OnePlus One
  12.1
• Oppo Find 7a
  11.4
• LG G3
  11
• Xiaomi Mi Note
  11
• Samsung Galaxy Note 3 S800
  9.9
• LG G Pro 2
  8.7
• Meizu MX4
  7.9
• Samsung Galaxy A7 (S615)
  5.8
• Meizu m1 note
  5.8
• Samsung Galaxy Note 3 Neo
  3.7
• HTC Desire 816
  1.7

GFX 3.0 Manhattan (onscreen)

Higher is better

• HTC One M9
  24
• LG G Flex2
  22
• Samsung Galaxy S6
  14
• Asus Zenfone 2 ZE551ML
  13
• OnePlus One
  12.9
• Asus ZenFone 2 ZE551ML (4GB of RAM)
  12
• Oppo Find 7a
  11.4
• Xiaomi Mi Note
  11
• Samsung Galaxy Note 4 Lollipop
  11
• Samsung Galaxy Note 3 S800
  10
• LG G Pro 2
  9.2
• LG G3
  7.7
• Meizu MX4
  7.4
• Samsung Galaxy A7 (S615)
  5.8
• Meizu m1 note
  5.7
• Samsung Galaxy Note 3 Neo
  4.7
• HTC Desire 816
  3.9

Basemark X is a bit less flattering on the Zenfone, but in this company it still performs admirably. Of the old dogs only OnePlus One is ahead, and not by much.

Basemark X

Higher is better

• Samsung Galaxy S6
  27169
• Samsung Galaxy Note 4 Lollipop
  20043
• HTC One M9
  19848
• LG G Flex2
  19360
• Asus ZenFone 2 ZE551ML (4GB of RAM)
  13414
• OnePlus One
  13129
• Xiaomi Mi Note
  13075
• Asus Zenfone 2 ZE551ML
  12565
• LG G2
  11101
• LG G3
  10580
• Meizu MX4
  8324
• Samsung Galaxy A7 (S615)
  4802
• Meizu m1 note
  4617
• Xiaomi Redmi Note
  2974
• HTC Desire 816
  1437

Browser performance turned out very good as well. The JavaScript-intense Kraken 1.1 squeezed a 6360ms score from the Zenfone 2, the best result behind the obvious powerhouses. HTML5 is a non-issue too, as evidenced by the figures in BrowserMark 2.1.

Kraken 1.1

Lower is better

• Samsung Galaxy S6
  4154
• LG G Flex2
  4621
• Asus ZenFone 2 ZE551ML (4GB of RAM)
  5057
• Samsung Galaxy Note 4 Lollipop
  5181
• HTC One M9
  5500
• Asus Zenfone 2 ZE551ML
  6360
• Xiaomi Mi Note
  6382
• LG G Pro 2
  6578
• Oppo Find 7a
  6660
• OnePlus One
  7008
• LG G3
  7632
• Meizu MX4
  9408
• Samsung Galaxy A7 (S615)
  12266
• Xiaomi Redmi Note
  12416
• HTC Desire 816
  13564
• Meizu m1 note
  15055

BrowserMark 2.1

Higher is better

• Samsung Galaxy S6
  2718
• Samsung Galaxy Note 4 Lollipop
  2232
• LG G Flex2
  2086
• Asus ZenFone 2 ZE551ML (4GB of RAM)
  1853
• HTC One M9
  1681
• Samsung Galaxy A7 (S615)
  1655
• Asus Zenfone 2 ZE551ML
  1486
• LG G3
  1453
• LG G Pro 2
  1346
• OnePlus One
  1339
• Oppo Find 7a
  1327
• HTC Desire 816
  774
• Xiaomi Mi Note
  748
• Meizu MX4
  720
• Xiaomi Redmi Note
  588
• Meizu m1 note
  536

To wrap up, the Zenfone 2 ZE551ML proves to be a strong performer, even in this compromise configuration with 2GB of RAM and Intel Atom Z3560. While it may not be on par with the latest and greatest, it outperforms established flagship names from the previous generation and shows no apparent weaknesses. We can only imagine what the top model would have shown in these tests with double the operating memory and higher maximum clock speed.