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[Experience Sharing] ASUS 5Z ZS621KL In-depth Review - Rise Of A New Flagship Killer

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mail2ronit IND Dr. Zen(IN) | All posts
Last edited by mail2ronit on 2018/8/2 16:39

ZF5Z Cover FR.jpg

The ASUS 5Z has taken the affordable flagship market by storm in India. Thanks to it’s affordable price point, many people are considering this one & it’s my responsibility to test the device head to toe before I give you my final opinions on it.

I’ve tested the ASUS 5Z extensively for about two weeks now & I’m ready with it’s scorecard. So this, is my ASUS 5Z comprehensive Review.

So, if you regularly read my reviews then you probably know who we go here. However, if you’re reading for the first time, we generally start with the specs, then check out the evaluation part by part & finally come to the conclusion. So, let’s roll the specs sheet.

ASUS 5Z ZS621KL Specifications

ZF5Z Specs FR Compressed.jpg

Design & Build Quality


The ASUS 5Z takes design motivation from the previous two generations of its ancestors & takes the approach to a new level. What it means is that, the design approach does somewhat resemble the ASUS 4 & ASUS 3 but, it has been improved on a huge scale. The ergonomics are way improved now & the Glass Sandwich design looks more premium. The device is wrapped in Corning Gorilla Glass 3 & the Concentric Design looks way better as well.


The Gorilla Glass however, can get Micro-scratches however so, I’ll recommend a case & a Tempered glass. ASUS supplies a silicon TPU case in the box & I’ll definitely recommend to use that instead of using the Phone completely naked.


The power & volume buttons are made out Metal & they are quite clicky & fairly tactile, not way too much though. But, is this phone brittle though? I will say that, it is just as brittle a you would expect Glass to be. Accidents can definitely happen & that’s why I recommended a case in the first place. Overall, I liked what ASUS did with the design because, it makes the device feel premium but, I still wish that they’ve gone with Corning Gorilla Glass 5 instead of 3. Otherwise, good job ASUS.

The Display


The Super IPS+ Display is 6.2 inches diagonally & spots a resolution of 2246x1080 which means it’s a Full HD Display with a near 19:9 Aspect Ratio and that means, we do have a Notch here. Now, though the Notch isn’t one of the favourite elements for many people but, for me, it took about 10 to 15 minutes before the Notch stopped bothering & I didn’t even think to hide the Notch afterwards. While watching videos or playing games, there's also an option to view in "Standard" or "Full Screen" mode which helps you to select if you want the side areas of the Notch to be visible or not.


Now, talking about the actual Display quality then, it’s pretty good. It’s an IPS panel so, the Blacks are not as pronounced as like on the AMOLED panels but, for an IPS Display it’s literally one of the best IPS panel that is currently available on any smartphone. The contrast ratio is pretty good & the colors look well pronounced. The Display supports about 100% of the DCI-P3 Color Gamut which allows it to show those wide range of colors that aren’t visible in general sRGB color gamut. However, there is an option in Display Settings where you can choose between “Wide” (P3) or Standard (sRGB) gamuts depending on your preference.

Hardware & Performance


The ASUS ASUS 5Z is build with Flagship Hardware which means it should be pretty good in terms of performance right? Well, practically yes but this phone does a few things a little bit differently. We will get into that but, let’s do a brief evaluation of the Hardware first.

So, ASUS 5Z is powered by the top of the line Snapdragon Flagship. The Snapdragon 845 is based on the 2nd gen 10nm Process Technology which is significantly better in Performance & Power Efficiency compared to its predecessor which came with the 1st Gen 10nm Process Technology. The Kryo 385 cores here are arranged in a big-little architecture. There are four High-performance cores clocked at 2.80 GHz & four Power-efficiency cores clocked at 1.77 GHz. My review unit had 6 Gigabytes of LPDDR4X RAM but, there is an 8 Gigabyte RAM variant as well.

The GPU is an Adreno 630 which also based on the same 10nm Process Technology & it is clocked at 710 MHz & it supports OpenGL 3.2, OpenCL 2.0 & Vulkan 1.1 APIs in games. So, newer games should be compatible with the GPU.

For those benchmark hungry people, here are some test results I got during several benchmarking tests,

ZF5Z CPU Benchmarks.png

ZF5Z GPU Benchmarks.png

ZF5Z Storage Benchmarks.png

Talking about the Real Life performance, the device feels fast & snappy. It’s probably one of the top 3 fastest devices in production right now. The apps opening speed is fast, the overall UI feels snappy & the RAM management is dynamite. If you don’t want to go with the 8GB RAM variant, you can easily get away with 6GB RAM variant. The Snapdragon 845 here has it’s AI Engine enabled so, there are several AI features integrated into this one which we will discuss later in the software section.


Playing games was also a great experience on this one. I have thrown in games like Asphalt 8, PUBG, Galaxy On Fire 3, Need For Speed: No Limits & Godfire. This phone handles games like a charm & keeping the Graphics settings to the maximum, this device plays the demanding games pretty smoothly which means the GPU optimization has been done well. Also, Godfire is a game that even flagship GPUs struggle to play & the Adreno 630 played it the smoothest till date. So, I have to say that I’m pretty impressed here.

ASUS packs UFS 2.1 Storage in the ASUS 5Z which in my case was 64 Gigabytes in capacity. However, there are two more storage variants with capacities of 128 Gigabytes & 256 Gigabytes. The speeds in the 64 Gigabyte vaiant goes to 685 MBPS Read & 152 MBPS Write which is pretty impressive.

Battery Life & Thermals

ZF5Z SOT.png

So, it finally brings us to the Battery Life. So, with all these high performance hardware elements, that 3300 mAh Battery is able to provide a full day of use & you’ll need to plug in your phone at the night. I was able to get about 5 hours of Screen-on-time on average day-to-day use case scenario. There is support for Qualcomm Quick Charge 3 which juices up the Battery in about 65 minutes (2%-100%). There is also support AI & Scheduled charging which can be useful to extend the longevity of the battery.

Talking about the thermals, I generally didn’t find the device to overheat in day-to day use case scenarios, even while gaming the phone maintains reasonable temps. The only time I saw the device getting pretty hot was, when I was using the Camera for an extensive period of time. Overall, the device was maintaining reasonable temperatures.



The Software is the key that deals with the usability of your hardware or in simple words software is making your hardware work. But, these Operating Systems along with their User Interfaces do a lot more by adding some really useful features on top.

ZenUI is definitely not the most prefered user interface ever because, it used to be pretty heavy but, the ZenUI 5 built on top of Android 8.0 Oreo is way lighter & way smoother compared to its predecessors. The navigation feels really snappy on this one & the apps open pretty fast too. As I mentioned earlier, the RAM management is pretty damn good so, the software manages the apps pretty well & does a good job at keeping them loaded into the memory until you dismiss them yourself. There is also app suggetions where the device can show five most frequently used apps below the App Drawer area for quick access.


However, all these improvements are definitely a welcome effort from ASUS but, what about all the AI features that they are telling us about & biggest question of all, do all these features  really make a difference? Well, they kinda do but, it depends on the user if they want the extra features or not.

ZenUI 5 now has a ton of AI features including Optiflex, AI Boost, AI Charging, AI Ringtone & more.
Optiflex optimizes the app usage & check how frequently you are using an app & defines processes & allocates memory accordingly for it when it’s running on the background or even when you’re not using it. AI Boost also optimizes the app activities & RAM but, also opens up the SOC to its maximum potential so it can deliver the maximum performance.


With AI Ringtone, the device detects the sound signature of its surroundings & adjust the Ringtone Volume accordingly. So, if the surroundings are loud, the Ringtone Volume will be high & if the surroundings are quite, the Ringtone Volume will be comparatively lower. There is also something called the AI Gallery which literally suggests filters for your photos & learns your preference based on if you wish to keep the suggested filters or not.


AI Charging learns your sleeping habits & charges the device in a way that tries to improve the longevity of the Battery. So, if you plug it in before you go to the sleep, the device will charge from 0%-80% with traditional Fast Charging method & does the rest just before you wake up in the morning.  There is even a Smart Screen On feature that keeps the screen on when you’re looking at it. So, basically the Front Camera is tracking your face but, also using your eyes as a trigger to determine if you’re actually looking at it or not. This process requires the Front Camera to stay on which drains the Battery a little quicker. So, keep that in mind if you plan on using it.


Finally, there's Zenimoji which basically are animated emojis from ASUS. We have a quite a few options to choose from here including Zenny, a few animals & a couple of human like figures. It uses 2D Face Tracking to replicate our facial expressions & the ASUS 5Z can videocall or even livestream with these Zenimojis. It works okay but, it's 2D Face Tracking so, it's not very accurate if that matters to you.

Now, let’s talk about the issues I ran into during my test period. So, the first issue was with the AI Boost trigger. I have tried benchmarking the device with both AI Boost enabled & disabled but, sometimes even with AI Boost disabled I got Full Fledged benchmarking scores which means, the AI Boost wasn’t disabled in reality. So, the Software was not turning off AI Boost sometimes. Also, the Biometric Security options were getting disabled sometimes so, I was forced to unlock my device with my pattern instead of Face Unlock or Fingerprint Scanning. I hope ASUS can solve these issues soon with a Software update.

The Cameras


The ASUS 5Z comes with a Dual Camera setup on the back. However, this time the implementation is a little bit different compared to what the competition is offering. Instead of using the second camera as a Telephoto or Depth Sensing one, ASUS has thrown in a Wide-angle lens into the game.

The main shooter spots a 12MP IMX363 sensor from Sony which is actually a Flagship sensor & the successor to the IMX362 that we’ve seen in the ASUS 4, ASUS 4 Pro & even the ASUS Zoom S.

The IMX363 has the exact same sensor & pixel size like it’s predecessor. So, a sensor size of 1/2.55-inch & Pixel Size of 1.4 micron. The larger pixels coupled with f-1.8 aperture are intended to make the low-light performance better simply by capturing more light into the sensor.

Regular Wideangle.png

That secondary Wide-angle Camera spots an 8 Megapixel sensor from Omnivision & the lens has an aperture of f-2.2. The 1/4-inch OV8856 sensor has a Pixel Size of 1.12 micron which is pretty typical for most of the mid-range smartphone sensors right now.

Overall, the images turned out to be pretty good from both the rear facing cameras. The daylight performance was pretty impressive on both cameras & in low-light the 12MP Main Camera performs way better compared to the 8MP Wide Angle one. The Wide-angle Camera mainly helps with that extended or extra area portion in photos when needed.

Here are some Camera samples,









The 8MP Front Facing Camera houses the exact same sensor as the Wide-angle one. So, an Omnivision OV8856 with 1.12 micron Pixels. However, the aperture here is f-2.0.


The daylight shots on the Front Camera came out well & in moderate artificial lighting, the images were okay as well. If the lighting conditions are very low, it’ll show a significant amount of noise.

Here are a few samples from the Front Facing Camera,





Now, I have done a dedicated Camera review for this device so, if you need more samples & detailed discussion, please check out the Camera Review by clicking on the link given below.



There is quite a bit emphasis on the Audio in the ASUS 5Z. There are Dual Stereo Speakers where the Earpiece doubles as a secondary speaker & both the speakers have there own NXP Smart Amplifiers. In real life the speakers get reasonably loud & while the Highs & Mids come out from the main speaker on the bottom, the Lows come out from the top one. This solution works really well & I loved the speaker audio from this one.

There is a 3.5 mm Headphone Jack which supports 24-bit Hi-res Audio along with 7.1 DTS Virtual Surround Sound. You need supported headphones to be able to hear those Hi-res Audio files but, thankfully the included ZenEar Pro supports Hi-res audio. I’ve listened to some 24-bit FLAC audio files with the included earphones & the sound output was pretty good.

The Verdict


The ASUS 5Z is really well made device with some really interesting features & a capable pair of Cameras. It starts at a price of 29999 INR for the 6GB, 64GB with the 6GB, 128GB variant priced at 32999 & the 8GB, 256GB variant priced at 34999. This makes the ASUS 5Z a really good package compared to what the nearest competitors are offering. But, is it still a value for your money? Let’s break it down with pros & cons.

1. The Display is rich & color accurate
2. The Gaming Performance is top notch
3. The RAM Management & Multitasking experience are pretty good
4. The AI in the Camera does not over-do things if much change in the image isn't needed
5. Low-light preformance is pretty good on the Main Camera
6. The Stereo Speakers & the output via. the Headphone Jack are great
7. Most of the AI Features turned out to be helpful

1. The Software still needs work
2. It's using the older Corning Gorilla Glass 3
3. The Cameras struggles with Dynamic Range when the subject is back-facing the Sun

So, do I recommend the ASUS 5Z? Well, I absolutely do recommend it & I think that what you’re getting here is a really good value of the money that you need to invest. No the Cameras are not going to compete the top end flagships any day soon but, those flagships are also way pricy. Sometimes the price is more than double of the ASUS 5Z. So, I think if you want to save some cash & still get that Flagship experience, the ASUS 5Z is the best value that you can get on the market right now.

So, that's it for the full in-depth review of the ASUS 5Z. Let me know you views & questions in the comments section below. That's all for this series & I'll catch you guys very soon.

Former Dr.Zen Ronit Roy

Devices: ASUS 6Z , Zenfone Max Pro (M2) ZB630KL , Zenfone 3 ZE520KL , ROG G501VW , Zenfone Zoom ZX551ML , Zenfone 4 A450CG
IND Level 7 | All posts
Really very Appreciate article. I became your fan from this,  Ronit bro !  ✌️
mail2ronit IND Dr. Zen(IN) | All posts
RC_CREATURE posted on 2018/7/31 09:02
Really very Appreciate article. I became your fan from this,  Ronit bro !  ✌️

Thank you dude                                                                                                                                     

IND Level 1 | All posts
You have yet not tapped into the audio output that a smartphone can give in terms of earphones. The earphones provided with the 5Z are okay and not that great as hyper-marketed. The DTS X does give some effect to the sound quality but is no way near to what Dolby Atmos does in smartphones. Moreover if you just switch to USB type C or cdla earphones, you will notice the difference.
mail2ronit IND Dr. Zen(IN) | All posts
Last edited by mail2ronit on 2018/7/31 19:00
kundan.bhardwaj1 posted on 2018/7/31 14:12
You have yet not tapped into the audio output that a smartphone can give in terms of earphones. The  ...

If you use higher quality headphones like the over the ear high-impedance ones from Sennheiser, the clarity will definitely be a lot better compared to what you're getting on the stock ZenEar Pro. Try with 24-bit FLAC files.

However, I do also wish that true Dolby Atmos was supported on this one. That would have definitely made the experience quite a bit better in some cases.
IND Moderator | All posts
Great article mate !!!! keep it coming....
mail2ronit IND Dr. Zen(IN) | All posts
Zen_Ro posted on 2018/8/2 14:40
Great article mate !!!! keep it coming....

Thank You Zen_Ro                                                                                                                              
mail2ronit IND Dr. Zen(IN) | All posts
Last edited by mail2ronit on 2018/8/2 15:55
Zen_Ro posted on 2018/8/2 14:40
Great article mate !!!! keep it coming....

More content coming soon                                                                                                                     
IND Level 1 | All posts
I am using ASUS 5z almost 20days
I am posting reviews  after using this phone.
Camera has Dynamic Range issue when the subject is back-facing the Sun or brighter side, focus issue, front camera is very buggy and noisy, video calling is very noisy while using social media like whatspp, hike...etc

Battery is draining rapidly in standby mode also.

Tv casting is unstable.
Raw is always looks like full even no apps are running in the background. 
Device is Heating sometimes while charging or playing games.

Please Asus fix these issues..
Otherwise phone is working well
mail2ronit IND Dr. Zen(IN) | All posts
Ni3 posted on 2018/8/2 16:01
I am using ASUS 5z almost 20days
I am posting reviews  after using this phone.

Hey, thanks for the inputs.

Can you tell me how exactly you're trying to cast?
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