In depth review of Asus ZenBook S UX391UA

Perfect for what it is meant for

The ASUS ZenBook S UX391UA is an honest laptop that is not trying to be something it is not. It is small, elegant, ultra portable, fast and quality built. It is perfect for multitasking operations like office tasks, Photoshop, writing, reading, coding, surfing, file management, social media and so on. And if you just need a small and powerful laptop without gaming capability this is a very good choice.

It is probably quite useless for demanding games or 3D applications because this laptop does not have a dedicated graphics processor. Even if it did it would probably just overheat and thermal throttle. In other words: this laptop is great for what it is intended for and bad at other stuff like gaming.

Technical specifications

  • Model: ASUS ZenBook UX391UA
  • OS: Windows 10 Home 64-bit Edition
  • CPU: Intel Core i7 (8. generation) 8550U / 1.8 GHz
  • RAM: 16 GB LPDDR3 SDRAM 2133 MHz
  • Storage: 512 GB SSD – (M.2) PCIe – NVM Express (NVMe)
  • Screen: 13.3″ 1920 x 1080 (Full HD) LED LCD
  • Graphics: Intel UHD Graphics 620
  • Camera: HD Web Camera
  • Sound: Harman/kardon-stereo speakers and microphone
  • Keyboard: Backlit keyboard and touchpad
  • Wireless: 802.11ac, Bluetooth 4.2
  • Battery: 4-cell lithium ion 50 Wh up to 13.5h
  • Power: IN: AC 120/230 V (50/60 Hz) OUT: 65W, 19 V, 3.42 A
  • Ports: 3.5mm jack audio output 1 x USB-C 3.1 Gen 1 (Power Delivery/data/video)  2 x USB-C 3.1 Gen 2/Thunderbolt 3 (Power Delivery/data/video)  HDMI (on the included adapter) USB-C (on the included adapter) USB 3.0 (on the included adapter)
  • Security: TPM Security Chip and fingerprint reader
  • Size: 31.1 cm x 21.3 cm x 1.29 cm
  • Weight: 1.05 kg

Design and build quality

The outside chassis is beautiful and made of brushed shiny dark blue metal with golden lines around the device. Once you touch it you immediately get that luxury feeling. Once you open the laptop the inside is made of something between hard plastic and soft metal, I am not really sure what it is but it feels like the same material used on the latest MacBook Pro keyboard. This is also dark blue and very light.

The blue version has a back-lit keyboard with keys with brown-ish/peach letters. They go great together with the golden lines around the laptop. If you are used to and like the ZenBook designs you will love this one. I really have no complaints when it comes to design. Although I have neither, this would fit right in a private jet or a Lamborghini.

Keyboard, touch pad and fingerprint reader

First things first. This is a major drawback for me. For some really odd reason Asus actually decided to move the [*’] button up a row on the Nordic keyboard version of the laptop. Probably because there was not enough room to fit the extra button on the Nordic keyboard, since we have an additional three letters. This is a pretty dick move if you ask me. I mean it is one thing to switch keys like Lenovo does with the Fn key and the CTRL key. But seriously… it is pretty arrogant to just completely move a letter key to another location. It is like they just completely ignored the fact that this will upset (probably every) Nordic customer. I guess you get used to it after a while, but since I am also using three other computers it is going to take a while.

The touch pad has a very smooth surface and feels very light to the touch when you press a button. First thing you notice though is that it is quite small. This is not a bad thing as the whole concept here is to reduce size and make the laptop ultra portable. The touch pad is adequate and I had no problems with it.

For me, the keyboard was a little disappointing. I think you would either love it or hate it, but to me the keyboard feels a little like a MacBook Pro rip-off. It is hard to explain but the keys feel just a little too loose and “cheap”, almost “toy-ish”. I mean you do get used to them after a while, but I would rather have the keys a little more “tight” and solid. It is almost like comparing the keys of a electric keyboard with a piano keyboard. I would prefer the heavy keys of a piano instead of the light plastic keys of a musical keyboard. Having said that, I did write this whole review on the laptop and it was not a big drawback for me so I will not overemphasize here.


The screen colours are balanced an adequate. For simple photo editing the screen is really good. Although the screen is just FHD (1920×1080), for a 13″ screen that is not too bad. For me unfortunately, glossy screen is just annoying. It looks great aesthetically, but when you sit outside or have direct sun behind you the screen will reflect a lot. Almost all touch screens are glossy, but this is not a touch screen so I am a bit disappointing here. Apart from that the screen does a good job being balanced and just sharp enough to do the details. The brightness is OK, but I am doubtful if the screen has enough brightness outside in the sunlight.

Ports and connectivity

The laptop simply has three USB-C ports but you do get a adaptor included with HDMI, USB and USB-C. I like the fact that Asus moves forward on this. In a couple of years you are not going to want USB-A anymore. This also allows you to chose if you want to charge the laptop from the right side or the left side. The only other port on the computer is an audio output on the right side of the screen.


When I first saw this computer I was surprised by the “hinge” design that tilts the body of the laptop up from the surface. First thing I was thinking was that this is a good way to levitate hot air from under the laptop since most of us often have the laptop on put lap. However I soon discovered something very unorthodox. The exhaust vents are located at the top of the laptop just in front of the bottom of the screen. This is even better. Now you can rest the laptop on your lap without worrying about covering the exhaust vents. Unfortunately even if this is the case the laptop does get very warm. While setting up the laptop (installing some software and downloading) the laptop CPU had a temperature of around 70 to 80 degrees Celsius. That is a lot for trivial operations like installing Photoshop if you ask me. It seems like this is a CPU design issue. It feels like the CPU is a little overzealous once it fires up and generates a lot of heat. At one point the laptop was so hot that I could barely keep my hand on the surface of the under side. That might not be a problem, but I am a little worried that this will cause the laptop components to degrade over time.


Here is the thing. The sound coming from the UX391UA is really strange. Do not get me wrong here. It is in general very quiet and I am extremely sensitive to loud computer noises. But the character of the sound is really weird. It almost sounds like the sound a mechanical hard drive makes when it is writing to the disk. I have heard the same noise coming from other laptops with Intel 8550U processors, but I am not sure if this is indicating that something is broken.

Note that the volume here is compressed to make the sound more audible.

The sound is not really annoying or anything, it just makes me worried that there is something wrong. The computer works like a charm though so I might just be a little paranoid.

EDIT: So I got the device replaced by another one and it turns out that the sound is exactly the same on the replacement. I guess it is safe to assume that the sound is just normal and nothing to worry about.


The laptop came with a cleaning cloth, a USB-C adapter and beautiful, quality made sleeve for the laptop.

The USB-C adapter features a HDMI port (not sure which version), a USB port and a USB-C pass through port.

Performance and benchmark

Although the UX391UA is not designed as a workstation or gaming laptop, it still features a high end Intel i7 CPU that is designed to handle demanding tasks. This laptop is blazing fast and the only time I had to wait for the computer was when it was encrypting the drive while I was installing two applications and had multiple tabs in Chrome open all at the same time while the computer was also indexing the Start search results.

To test the computer a bit more clinically I ran Passmark to get some numbers.


The laptop comes with a Windows 10 Home license that I upgraded to a Windows 10 Pro licence. The laptop did of course include Windows 10 “bloatware” such as Candy Crush and Linkedin, but I assume that is unavoidable nowadays.

The UX391UA came with a lot of bundled Asus software such as:

  • ASUS Battery Health Charging
  • ASUS Device Activation
  • ASUS GiftBox Service
  • ASUS Hello
  • ASUS Keyboard Hotkeys
  • ASUS Live Update
  • ASUS Product Registration Program
  • AudioWizard ICEpower
  • eManual
  • MyASUS-Service Center
  • Quiet Fan
  • Realtek Audio Console
  • Splendid
  • WinFlash
  • ZenAnywhere

For a full list of installed software click here. I would love to see Asus consolidate all these apps into one like Lenovo did with Lenovo Vantage (previously called “Lenovo companion”).


This laptop is super convenient and inconvenient at the same time. On one hand it is light, robust and small. This makes it the perfect companion for busy writers, content creators or programmers on the go. However the laptop has flaws that should never have made it to production if you ask me. Moving one of the most essential keys for Nordic customers is just plain arrogant. Having a glossy screen is only a drawback when the laptop doesn’t even feature a touch screen. The laptop is also bottle necked by the a bad heating solution which results in CPU throttling.

It is a solid and good office-laptop for most people, but I would not recommend it for the most demanding computer tasks or for Scandinavian customers. The only reason I would recommend it right now is because it is better than its competitors at the moment.

+ Very light and compact + Stylish and elegant + Powerful and fast + 3 USB-C ports + adaptor

- Throttles CPU on heat – Reflective glossy screen – Keyboard feels a little cheap – Nordic keyboard is messed up – Easily gets finger marks

Verdict: ★★★★☆☆