The second half of 2017 is finally the right time to buy an all-round ultra-portable laptop that can handle standard everyday activities such as browsing, movies or music, but also games, graphics editing, and some other more demanding chores.
And that’s because Intel has unveiled their first quad-core ULV platforms and Nvidia has updated their base-level dedicated graphics. The Asus Zenbook UX331UN is one of the better devices that put both these hardware novelties in a compact and light 13-inch body, and the results are a significant step-up from anything similar available in the last years. We’ve spent some time with the Zenbook UX331 and you can find all our impressions below.
You should know from the beginning that Asus will offer this laptop in a multitude of hardware variants. We’re talking about a pre-production base-level model in the article, with a matte FHD IPS screen, a Core i5-8250U processor and Nvidia MX150 graphics. Read on to find out where this laptop shines and where it comes short.
Specs as reviewed
||Asus Zenbook 13 UX331UN
||13.3 inch, 1920 x 1080 px, IPS, non-touch, matte
||Intel Kaby Lake-R Core i5-8250U CPU
||Intel UHD 620 + Nvidia MX150 2 GB GDDR5
||8 GB DDR4 (soldered)
||512 GB SATA SSD (M.2 80 mm)
||Wireless AC (Intel Dual Band 8265), Bluetooth 4.1
||2x USB-A 3.1, 1x USB-C 3.1 gen 1, HDMI, microSD card-reader, headphone/mic jack
||50 Wh, 65W charger
||310 mm or 12.20” (w) x 216 mm or 8.50” (d) x 13.9 mm or 0.54” (h)
||2.49 lbs (1.13 kg)+ .53 lbs (.24 kg) European charger and cables
||backlit keyboard, VGA webcam, stereo speakers
The UX331UN will be available with either Core i5-8250U or Core i7-8550U processors (both quad-core KabyLake-R low-voltage), 8 or 16 GB of DDR4 memory (soldered on the motherboard), with or without the Nvidia graphics, with M.2 SATA or M.2 NVMe storage, and with three screen options to choose from: matte and touch FHD panels, as well as an UHD IPS touchscreen.
The best buy in our opinion is the Core i5-8250U model with MX150 graphics, 16 GB of RAM, NVMe storage and the matte FHD IPS screen. Our test unit gets only 8 GB of RAM and SATA storage, but is otherwise identical to the ideal configuration, especially since the SSD can be replaced with a faster unit if wanted.
Update: In the meantime, our review of the 2022 Asus ZenBook S 13 update is available here, built on the newer Ryzen 7 6800U hardware platform.
Design and first look
This laptop is thinner and lighter than the Dell XPS 13 and the reduced weight is the first thing you’ll notice when you’ll take it out of the box. It’s not as compact as the XPS 13 though, and not at sturdily built either. You might wonder why I’m comparing it to the XPS 13? Well, I’m very familiar with the XPS that has been my ultra-portable of choice for the last years, and the XPS is for many the standard in the 13-inch niche of thin-and-light notebooks where the Zenbook UX331 plans to compete as well.
Anyway, while there’s some flex in the lid and in the main body of the UX331UN, I don’t think potential buyers should worry about that. The build quality is good, just not as solid as with a few of the alternatives. Metal is used for the entire case, with a glossy finishing for the lid-cover (Asus calls it gloss-like, but it’s not that shinny) and the classic smooth finishing for the interior, sides, and underbelly that we’ve seen on previous Zenbooks. The inner chassis is still made out of plastic, which partially takes the blame for the flex, alongside Asus’s choice of using a thin sheet of metal on the hood. These two on the other hand help lower the weight, so it’s a lose some, win some (little, though) situation here.
Our sample is overall carefully crafted and finished, except for the fact that the bottom still doesn’t attach flush to the sides, leaving some gaps and sharp edges, as you can see in the pics below.
You should note that our unit is a pre-production sample, but I’ve noticed this similar issue on the vast majority of Zenbooks I’ve got my hands on in the last years, so I expect it will be there on the retail UX331s as well. For some reason, Asus has a hard time joining these two parts properly together. You might say I’m nitpicking, and perhaps I am, but when these edges bite into your fingers you’ll understand why this small aspect is actually quite annoying in daily use.
Back to the form-factor, this Zenbook is still one of the most compact 13-inchers available out there, and the extra mm in length and width over the XPS 13 actually leave room for slightly bigger palm-rest and enough space on the top bezel to actually put the webcam on top of the screen, where it should be.
Before we move to the impressions gathered from using this laptop in the last weeks, I should also add that Asus offers it in two color options, both nice and rather unique: the Slate Grey that we have here, and the Royal Blue we’ve seen on the Zenbook UX370 tested recently, as well as on other Zenbooks. Although that Blue model looks gorgeous, I believe smudges and fingerprints will show a lot easier on the gloss-like lid of this version, so I’d personally opt for the Grey model if possible.
BTW, it’s beyond me why Asus keep pushing these glossy lid coatings. Perhaps they don’t scratch as easy as a standard metal surface, at least that’s my impression, but otherwise, they show a lot of smudges and are difficult to keep clean. At least it’s a step-up on this unit from the NIL plastic used on the Zenbook UX430, but personally, I do prefer standard metallic finishings, like on the Macbooks, the XPS lines, or the Zenbook UX550.
Anyway, I had a great time using this compact notebook. I didn’t actually notice the weight loss over my XPS 13, but if you’re coming from an older laptop you’ll enjoy only having to carry around a 2.5 lbs computer (and the extra .25 charger). The screen, on the other hand, is very easy to lift with a single hand and has a nice mechanical sound when shutting off. There’s a crease on the front for your fingers to grab it from and the edges are blunt and friendly, both around the screen and around the interior. The hinge allows to easily adjust the display, but also keep it in place firmly. It only goes back to about 145 degrees though, and that can be limiting when using the laptop on the lap or on the thighs as I do. It’s good enough for desk use though, where the rubber feet on the bottom also help to keep the computer well anchored in place, despite its reduced weight.
Speaking of the bottom, it’s pretty simple, with some air intake cuts on the laterals and speaker cuts on the front. Given the hardware inside and the overall height of just 13.9 mm, those intake cuts are not ideal imo and can spell trouble, but we’ll get to that in a further section. Hot air is blown out through the grills behind the hinge, and at least there’s enough space here to allow proper airflow.
The ports selection is alright, but not great for this day and age. You’ll find two USB A slots and full-size HDMI connector on the sides (1.4 according to the official website, so that means it won’t power a 60 Hz 4K screen). There’s also a USB-C port, but without Thunderbolt 3 support, and the cherry on top is the lack of a full-size SD card-reader, replaced by only a microSD card reader.
Regular users won’t have an issue with this kind of IO, there’s HDMI for video output and there are enough USB slots for everyday use. The lack of Thunderbolt 3, the lack of an HDMI 2.0 connection and the lack of a full-size card-reader, on the other hand, might steer professionals towards something else and that’s a problem, because there are 13-inch devices out there that offer some, if not all of them.
Keyboard and trackpad
The keyboard on this laptop has a lot in common with the keyboard on my XPS 13 and that’s a mixed bag. The keys are well spaced and sized and the layout is good, with the arrows keys a little bigger than on most other laptops in this class. We got to test the European model with the tiny Left Shift key and tall Enter, but that’s, of course, different with each region.
My gripe is with how this keyboard feels: the feedback is mostly alright, but there’s something about it that’s not right for me. The keys travel 1.4 mm into the frame according to the official page, but they feel shorter, like on the Zenbook UX550. They’re also a little spongy and at the same time require a firm hit to actuate, which in some cases means they won’t register a click that’s not perfectly aimed and pressed. In other words, this keyboard is unforgiving, which for me meant I could only type averagely fast and with average precision, even with a few thousands words in the bag.
So all in all, if you’re a heavy typist, there are ultraportables with better keyboards out there. The average user should get along fine with this one though.
Compared to my XPS 13, the Zenbook UX331’s keyboard was for me a little slower, but similar in terms of inaccuracy, just for different reasons. With the XPS it’s the shallow feedback, with this one it’s the high resistance and also the slight flex in the body that takes a toll. The UX331 types very quietly though and the keys are of course backlit, with three levels of brightness to choose from. The illumination is activated by hitting a key or swiping fingers on top of the trackpad.
For mouse, Asus went with one of their standard clickpads with Asus TouchPad drivers, which means there are very few customization options available. It’s a smooth and glidy class covered surface with nicely beveled edges around, so it feels nice to the touch and is easy to find in the dark.
The experience provided is pretty good out of the box, and even precise swipes work very well. The performance when keeping one finger on the surface and swiping with another is sometimes lackluster though, with the cursor getting sluggish and light taps not always registering properly in this case. That aside, because the lip between the clickpad and the front of the laptop is very narrow, it’s easy for parts of your clothes to get in contact with the surface when using this device on the lap and especially on the thighs, and when that happens the experience gets very erratic.
The physical clicks are nice and responsive, with the entire surface being clickable, just with less resistance towards the bottom corners.
There’s also a finger-sensor on this Zenbook, placed underneath the arrow keys, on the top-right part of the palm-rest. It’s responsive and works well with Windows Hello.
The Zenbook UX331 gets a 13.3-inch screen with fairly small bezels around and three panel choices: IPS FHD in a non-touch and a touch version, as well as IPS UHD touch. Our sample gets the former: the non-touch IPS FHD panel and it’s a pretty good option.
What I noticed from the first moment I got this notebook out of the box is that this screen is not completely matte like on the previous Zenbooks, it’s a little shinier and more reflective. That translates in extra glare when used outside or in bright rooms, but also less of the graininess usually associated with matte panels, so while I’m not necessarily a fan of this type of finishing, I believe most of you might actually like it better than the standard matte screens, especially if you mostly use your laptop indoor.
For the panel itself, Asus went with a rather average AU Optronics option, capable of roughly 275 nits of maximum brightness and mid-range contrast and color reproduction, as you can see below (data taken with the Sypder4 Sensor). We’ve seen variants of this panel on a few other mid-range ultraportables like the Zenbook UX330, Acer Aspire S13 or the Lenovo ThinkPad 13.
- Panel Hardware-ID: AU Optronics AUO492D (B133HAN04.0);
- Coverage: 98% sRGB, 71% NTSC, 75% AdobeRGB;
- Measured gamma: 2.4;
- Max brightness in the middle of the screen: 275 cd/m2 on power;
- Contrast at max brightness: 650:1;
- White point: 8700 K;
- Black on max brightness: 0.42 cd/m2.
The white point is greatly tilted towards Blue out of the box, but calibration will mostly fix that and balance the gray-levels. You can also use our calibrated profile available over here.
All in all, most will probably find this screen good enough for daily use. On top of all the aspects mentioned already, I’ll also add that I didn’t notice any obvious light bleeding and pinching around the bezel. But even so, this is not as bright or as rich as what you can get on other laptops in the segment, and you’ll especially notice the limited brightness when using the laptop in bright places, where the slightly reflective finishing won’t help either.
That aside, for now, I can’t tell you anything about the panels on the touch FHD and UHD versions, but I’ll update this section once I know more. Whether a touchscreen is useful on a clamshell laptop is entirely up to you, but what I can tell for sure is that the UHD screen is going to be expensive and will take a major toll on battery life. But at the end of the day, choose what best rocks your boat, just be aware of what each option implies.
Hardware, performance and upgrade options
The hardware inside is what actually puts this laptop on the map and the main reason you’d want to buy it.
As we mentioned earlier, the Zenbook UX331UN will be available in a bunch of configurations and we got to test one with an Intel KabyLake-R Core i5-8250U processor and Nvidia MX150 graphics, as well as 8 GB of DDR4 RAM and a 512 GB SATA SSD. That’s one of the base level models, but as you’ll see below, it’s also one of the better value ones.
The amount of RAM is the single issue here, as it’s soldered on the motherboard and non-upgradeable, and while 8 GB of memory are enough for daily use today, if you plan to push this computer through heavier loads or keep it along a for a few years, you’ll probably want to opt for the 16 GB configurations instead. Hopefully Asus will offer Core i5 models with 16 GB of RAM, as in the past that has only been reserved for their i7 models that are more expensive, without adding much in terms of performance. We’ll see.
The storage is upgradeable though and for that you’ll need to get past the entire back panel. It’s hold in place by T5 screws that are visible around the laterals (careful they’re not the same size, take note where each comes from for reassembly), but also two more Philips screws hidden underneath the rear rubber feet. You’ll notice the 80 mm M.2 slot inside, but also the battery, the plastic inner frame, the hinges’ mechanism and the fact that the Wireless chip is one of those newer compact veriants, and not the M.2 models used with most ultraportables.
Anyway, with that out of the way, let’s turn our attention on the hardware and how this laptop performs.
The Intel Core i5-8250U processor is a quad-core 15 W model, part of the Intel KabyLake-R series. Intel dropped the base clock speeds from their dual-core models in order to get four cores within this kind of TDP, but compensate with high Turbo Boost speeds, and as you’ll see below and in this detailed analysis on the Core i5-8250U CPU, this processor is a little faster than an i5-7200U in single-core loads and a major step-up from both the i5-7200U and the i7-7500U CPUs in multi-thread loads.
The images below show details on the speeds and temperatures registered with everyday activities. The CPU clocks-down to where it has to, so it performs well while staying efficient.
When it comes to high-load chores, you’ll notice that the CPU’s Turbo drops to 2.2 GHz in continuous loads. While the maximum Turbo Boost is advertised at 3.4 GHz, that’s for a single core, when all cores work simultaneously that kind of speeds can only be maintained for a few seconds and then the frequency stabilizes at 2.2 GHz (corroborated with the TDP limit of around 15 W). The Core i7-8550U behaves very similarly and due to the same TDP limitation, won’t run much faster, that’s why I find it hard to justify paying extra for it given it’s at least $100 more expensive then the i5. You might be forced to in order to get the 16 GB of RAM, as mentioned earlier.
This configuration also comes with Nvidia MX150 graphics, but there’s a catch: it’s down-clocked. GPU-Z mentions default clock speeds of only 937 MHz, with Boost Speeds up to 1038 MHz, but in games the Clock Speed averages about 1250-1300 MHz. That’s still around 250 MHz under a regular MX150 chip, as mentioned here or as observed on the Acer Swift 3 we tested a while ago. As a result, the GPU scores are lower on this implementation than on other laptops with Nvidia MX150 graphics.
Keep in mind we’re dealing with a pre-production sample here and things might change on the final retail units. However, a down-clocked version of the MX150 chip makes sense on such thin and compact laptop that would probably otherwise struggle to cool a full-speed version. And even down-clocked, the MX150 is a significant step-up from the integrated Intel chips and the Nvidia 940MX solutions that are available on some other 13 and 14 inch thin-and-lights. Still, let’s not jump to conclusions yet.
The pics below show more details on how the CPU and GPU performs in benchmarks and games on this unit, both when plugged in and when on battery. You’ll notice that everything looks solid as long as the laptop is plugged in, but the CPU throttles on battery, both in Cinebench and in games.
Anyway, as far as benchmarks go, we ran tests on our sample and here’s what we got.
- 3DMark 11: P3736 (Graphics: 3507, Physics: 5700);
- 3DMark 13: Sky Driver – 8507, Fire Strike – 2610, TimeSpy – 925;
- 3DMark 13 Graphics: Sky Driver – 8944, Fire Strike – 2848, TimeSpy – 829;
- PCMark 08: Home Conventional – 3216;
- PCMark 10: 3465;
- PassMark: Rating: 3520, CPU mark: 7945, 3D Graphics Mark: 1832;
- GeekBench 3 32-bit: Single-Core: 3354, Multi-core: 12684;
- GeekBench 4 64-bit: Single-Core: 4092, Multi-core: 13210;
- CineBench 11.5: OpenGL 62.51 fps, CPU 5.70 pts, CPU Single Core 1.64 pts;
- CineBench R15: OpenGL 86.39 fps, CPU 527 cb, CPU Single Core 143 cb;
- x264 HD Benchmark 4.0 32-bit: Pass 1 – 139.17 fps, Pass 2 – 31.41 fps.
However, I’d reckon this laptop might also be available without the Nvidia graphics, and in order to simulate that we disabled the Nvidia chip and reran benchmarks on what could potentially be a Zenbook UX331UA Core i5-8250U configuration. Here’s what we got:
- 3DMark 11: P1862 (Graphics: 1664, Physics: 6250);
- 3DMark 13: Fire Strike – 1041, Time Spy – 405;
- 3DMark 13 Graphics: Fire Strike – 1130, Time Spy – 353;
- GeekBench 3 32-bit: Single-Core: 3452, Multi-core: 13335;
- GeekBench 4 64-bit: Single-Core: 4053, Multi-core: 13220;
- CineBench 11.5: OpenGL 44.36 fps, CPU 5.98 pts, CPU Single Core 1.63 pts;
- CineBench R15: OpenGL 47.93 fps, CPU 488 cb, CPU Single Core 124 cb;
We also ran a couple of games on our sample and here’s what we got.
||FHD Ultra – MX150
||FHD High – MX150
|Far Cry 4
|Shadow of Mordor
|NFS: Most Wanted
|Total War: Atilla
As expected, these results are roughly 10-20% under what we measured on the Acer Swift 3 with the regular version of the MX150 chip, but even so the Zenbook UX331 can handle FHD gaming with High settings well and doesn’t throttle in any of the titles we tried on it.
I also tried to run the same games on the integrated UHD 620 graphics, by again disabling the Nvidia chip, but our sample Blue-screened fast in this scenarios so I don’t have any conclusions to share. There’s more about the performance of the Intel UHD 620 chip in this article, but all in all you should expect marginal gains over the regular Intel HD 620 on the Intel Core i7-7500U CPU.
Noise, Heat, Connectivity, speakers and others
There’s limited space inside the Zenbook UX331, but despite that the cooling solution implemented is different from anything we’ve seen on previous Zenbooks with entry-level dedicated graphics. There’s still a single fan and a single heatpipe, but the fan and radiator are actually placed in the middle, between the components, which means there’s a shorter distance between the components and the fins than on the older implementations and that should be a more efficient method of cooling them both. I still believe the airflow is sub-optimal with the limited intake cuts on the bottom, but even so, given how thin this laptop is, its thermal and acoustics behavior is better than I was expecting.
The fan is active all the time with daily use, but is quiet. At 37-38 dB, you’ll hear it in a perfectly quiet room (33dB room noise level), yet not that much otherwise. I didn’t notice any coil whining or electrical noise either. The fan remains surprisingly quiet with gaming as well, averaging 41-42 dB at head level, while most other laptops go above 45 dB in similar conditions.
The outer case temperatures average within normal margins as well. The laptop runs cool with daily use and although some parts of the interior get to high 40s and even low 50s with gaming, that’s not unexpected or unusual for a computer with this kind of build and hardware. The fact that the interior gets hotter than the underbelly is a little annoying though, as this causes sweaty hands while playing games for a longer period of time.
I still wish Asus would do something to improve the fan’s behavior with low-level use and allow a fanless experience. While the fan on the UX331 actually spins quieter than on other Zenbooks we’ve reviewed in the past, it’s still too aggressive and kicks-in unnecessarily early with everyday use.
*Daily Use – 1080p Youtube clip in EDGE for 30 minutes
*Load – playing FaCry 4 for 30 minutes
For radios Asus went with an Intel Dual Band 8256 chip that’s usually a very good performer. It performed well in our tests too as long as the notebook was kept close to the router or at least had a direct-line connection with it, but the performance dropped to barely usable levels at 30 feet with 2 walls in between. Keep in mind our sample is a pre-production unit with early drivers, so you might not run into this issue with retail models, but you should nonetheless keep an eye on this aspect and make sure your unit performs well when you get it.
The speakers are placed on the bottom and they are similar to the ones on the Zenbook UX430 and UX370. The Audio Wizard software didn’t work as it should on our unit though and as a result I can’t draw final conclusions on either volume or sound quality. You should however read our reviews of those other two Zenbooks to find out what to expect.
The last thing we’ll mention here is the webcam. It’s placed on top of the screen and flanked my microphones, but it’s the same crappy VGA camera that we’ve seen on the Zenbook UX490 and UX390, one that I wouldn’t want to use unless I had no other option. That’s another one of those things I cannot understand about these laptops: it would probably cost Asus a few dollars to put a decent HD camera on the Zenbooks, and yet they continue not to, so at the end of the day nobody will care that the camera is placed where it has to be,if it’s as bad as this one is.
There’s a 50 Wh battery inside the Zenbook UX331UN and that’s about average sized for this day and age. Since the battery life does not disappoint and this laptop is so thin and light, I’d reckon most potential buyers won’t probably complain about it. Here’s what to expect, with the screen’s brightness set at around 120 nits (~30 brightness).
- 7.4 W (~6 h 45 min of use) – very light browsing and text editing in Google Drive, Balanced Mode, screen at 30%, Wi-Fi ON;
- 6.4 W (~7 h 45 min of use) – 1080p fullscreen video on Youtube in Internet Explorer, Balanced Mode, screen at 30%, Wi-Fi ON;
- 4.8 W (~10 h of use) – 1080p fullscreen .mkv video in the Movie app, Balanced Mode, screen at 30%, Wi-Fi ON;
- 5.1 W (~10 h of use) – 4K fullscreen .mkv video in the Movie app, Balanced Mode, screen at 30%, Wi-Fi ON;
- 12.6 W (~4 h of use) – heavy browsing in Edge, Balanced Mode, screen at 30%, Wi-Fi ON;
- 27.5 W (~1 h 45 min of use) – gaming, Balanced Mode, screen at 30%, Wi-Fi ON.
I for one would have loved to see a bigger battery, even if that would have added a little extra to the weight and thickness. 50Wh is just too close to the bare minimum I’m willing to accept on an ultraportable and actually a step backwards from the older Zenbook UX330, which got a 57 Wh battery.
BTW, you shouldn’t forget this is the base level Zenbook UX331N. The i7 processor and the FHD touchscreen will take a toll on these numbers, and if you opt for the UHD display you can expect an extra drop of at least 25% if not more, which is one more reason why the UHD configurations are unbalanced and not worth getting, at least in my opinion.
The laptop comes with a 65 Wh charger with quick-charging and a full-recharge takes around 1 hours and 30 minutes. The wall plug is integrated withing the power brick, with non-retractable prongs, like on most other modern Zenbooks.
Price and availability
The Zenbook UX331UN is available worldwide and starts at around $999 in the US and 1000 EUR in Europe. This kind of money will get you the Core i5-8250U configuration with the Nvidia MX150 graphics, 8 GB of RAM and a 256 GB SSD. Higher-end models are also available.
Follow this link for updated info on configurations and prices at the time you’re reading the article.
There’s plenty to like about this Zenbook UX331UN and no real deal-breakers.
It’s light and compact, it’s fairly well built, it gets a decent screen and trackpad, and it can squeeze plenty from the quad-core Intel processors with Nvidia MX150 graphics inside while running fairly quiet, fairly cool and fairly efficient.
But the truth is, much like the Zenbook UX550 in its class, this laptop is only average in many ways: the build, the screen, the typing experience, the fan’s behavior, the battery size or the IO are just some of the aspects that are alright, not bad, but nothing to brag about either. Some users might not accept all these aspects, while for others this Zenbook would have to compensate with proper pricing policy.
Those of you in the former category that don’t care about gaming will find better value in the Dell XPS 13, with its brighter FHD matte screen, larger battery, and TB3 connectivity. Expect to pay more for it in most regions, though. There’s also the popular LG Gram 13 to consider, which doesn’t get the quad-core processors or the dedicated graphics, but it’s a nicely balanced ultraportable with a light build, 72 Wh battery, a fair price-point, and a pretty good QC record. The Lenovo IdeaPad 720s 13-inch is another interesting option out there, and if the budget allows, you could also aim for some of the Dell Latitude and Lenovo ThinkPad alternatives.
Those of you still in the former category that do care about gaming in a highly portable laptop, well, you’ll hardly find another alternative with a similar weight and silhouette, but you will find 13 and 14-inchers with a fully clocked Nvidia MX150 chip, as long as you’re willing to live with a larger and heavier build. The updated Acer Swift 3, the MSI Prestige PS42 and the Zenbook UX333 and UX433 lines (reviewed here and here) are the ones you should check out.
All in all, I believe the Zenbook UX331 is going to be a solid buy in the months to come for those of you that actually need the quad-core hardware and dedicated graphics, those of you interested in an all-round ultraportable that can handle multitasking and gaming as well. I expect Asus to push it in front of the crowd with a solid pricing policy as well, making some of its lacks easier to accept this way. Just make sure you understand what you’re getting here and where the competition might offer you better value for your needs and money.
That pretty much wraps this up, but the comments section is open and you should get in touch if you have anything to add to this review of the Asus Zenbook UX331UN, any feedback or any questions.
Our content is reader-supported. If you buy through some of the links on our site, we may earn a commission. Learn more.