Notebookcheck

Lenovo ThinkPad X1 Carbon 2020 Business-Laptop Review: 4K display costs battery runtime

More pixels including PWM flickering. Lenovo also offers the 2020 ThinkPad X1 Carbon with an optional glossy 4K screen, which is supposed to reach a brightness of 500 nits and also supports HDR contents. but how does the panel affect the battery runtime of the compact business laptop?
Andreas Osthoff 👁 (translated by Andreas Osthoff),

We have already reviewed the 2020 ThinkPad X1 Carbon from Lenovo and it is only a small update compared to last year's model, but it is still a very good and lightweight business laptop. Lenovo also offers the device with a glossy 4K HDR screen, which we will have a closer look at today. The additional price for the 4K panel is around 170 Euros in Lenovo's online shop. The configuration is otherwise identical to our previous test unit, so we will focus on the screen itself as well as the effect on the power consumption as well as the battery runtimes. Please see our previous reviews of the ThinkPad X1 Carbon for more information:

Lenovo ThinkPad X1 Carbon 2020-20U9003BGE
Processor
Intel Core i7-10510U 4 x 1.8 - 4.8 GHz, Comet Lake-U
Graphics adapter
Memory
16384 MB 
, LPDDR3-2133, Dual-Channel, soldered
Display
14 inch 16:9, 3840 x 2160 pixel 315 PPI, NV140QUM-N53, glossy: yes, 60 Hz
Mainboard
Intel Comet Lake-U PCH-LP Premium
Storage
Samsung SSD PM981a MZVLB512HBJQ, 512 GB 
, 434 GB free
Soundcard
Intel Comet Lake PCH-LP - cAVS
Connections
2 USB 3.0 / 3.1 Gen1, 2 USB 3.1 Gen2, 2 Thunderbolt, 1 HDMI, 2 DisplayPort, 1 Kensington Lock, 1 Docking Station Port, Audio Connections: 3.5 mm Stereo, 1 Fingerprint Reader, NFC
Networking
Intel Ethernet Connection I219-V (10/100/1000/2500/5000MBit/s), Intel Wi-Fi 6 AX201 (a/b/g/h/n = Wi-Fi 4/ac = Wi-Fi 5/ax = Wi-Fi 6), Bluetooth 5.0, Fibocom L850-GL, LTE
Size
height x width x depth (in mm): 14.9 x 323 x 217 ( = 0.59 x 12.72 x 8.54 in)
Battery
51 Wh Lithium-Polymer
Operating System
Microsoft Windows 10 Pro 64 Bit
Camera
Webcam: 720p HD
Primary Camera: 0.9 MPix
Additional features
Speakers: Dolby Atmos, 2x 2W, 2x 0.8W, Keyboard: Chiclet, Keyboard Light: yes, 65-Watt PSU, ThinkPad Ethernet Extension Adapter Gen2, 36 Months Warranty
Weight
1.095 kg ( = 38.63 oz / 2.41 pounds), Power Supply: 332 g ( = 11.71 oz / 0.73 pounds)
Price
2160 Euro
Note: The manufacturer may use components from different suppliers including display panels, drives or memory sticks with similar specifications.

 

Case - 4K ThinkPad with a different lid design

The case construction of the 4K model does not differ from the previously reviewed X1 Carbon with the 1080p screen, only the surface on the lid has a different carbon-fiber design. You can still see the usual black surface along the edges. Whether you like the design or not is definitely a matter of taste, but the surface does not attract fingerprints or dirt, respectively.

Display - 4K Panel with PWM

We already know the optional 4K panel from last year's model and even the Panel-ID is identical to the 2019 X1 Carbon we have reviewed before. The measurement results are slightly different, and our test sample is a bit brighter at 540 nits on average in combination with a slightly lower black value. The subjective picture quality of the glossy BOE panel (NV140QUM-N53) is excellent: High contrast ratio (~1600:1) sharp images, and rich colors.

However, there is a massive drawback: At a brightness level of 99% or lower, we can detect PWM at a very low frequency of 200 Hz, which can definitely result in problems. Backlight bleeding on the other hand is no problem, despite the high brightness.

Subpixel layout
Subpixel layout
Hardly any backlight bleeding
Hardly any backlight bleeding

Screen Flickering / PWM (Pulse-Width Modulation)

To dim the screen, some notebooks will simply cycle the backlight on and off in rapid succession - a method called Pulse Width Modulation (PWM) . This cycling frequency should ideally be undetectable to the human eye. If said frequency is too low, users with sensitive eyes may experience strain or headaches or even notice the flickering altogether.
Screen flickering / PWM detected 200 Hz ≤ 99 % brightness setting

The display backlight flickers at 200 Hz (Likely utilizing PWM) Flickering detected at a brightness setting of 99 % and below. There should be no flickering or PWM above this brightness setting.

The frequency of 200 Hz is relatively low, so sensitive users will likely notice flickering and experience eyestrain at the stated brightness setting and below.

In comparison: 51 % of all tested devices do not use PWM to dim the display. If PWM was detected, an average of 17916 (minimum: 5 - maximum: 2500000) Hz was measured.

550
cd/m²
575
cd/m²
548
cd/m²
545
cd/m²
574
cd/m²
534
cd/m²
505
cd/m²
539
cd/m²
493
cd/m²
Distribution of brightness
NV140QUM-N53
X-Rite i1Pro 2
Maximum: 575 cd/m² Average: 540.3 cd/m² Minimum: 14.1 cd/m²
Brightness Distribution: 86 %
Center on Battery: 572 cd/m²
Contrast: 1594:1 (Black: 0.36 cd/m²)
ΔE Color 4.7 | 0.6-29.43 Ø5.8, calibrated: 1.4
ΔE Greyscale 7.2 | 0.64-98 Ø6.1
99.4% sRGB (Argyll 3D) 73.8% AdobeRGB 1998 (Argyll 3D)
Gamma: 2.04
Lenovo ThinkPad X1 Carbon 2020-20U9003BGE
NV140QUM-N53, , 3840x2160, 14
Lenovo ThinkPad X1 Carbon 2020-20UAS04T00
BOE NE140FHM-N61, IPS, 1920x1080, 14
Lenovo ThinkPad X1 Carbon G7 20R1-000YUS
BOE NV140QUM-N53, IPS, 3840x2160, 14
Lenovo ThinkPad X1 Carbon 2019-20QE000VGE
LP140QH2-SPD1, IPS, 2560x1440, 14
Lenovo ThinkPad X1 Carbon 2019-20QES01L00
LP140WF9_SPF1, IPS, 1920x1080, 14
Response Times
331%
-29%
-4%
-26%
Response Time Grey 50% / Grey 80% *
47.2 (20.4, 26.8)
64.8 (30.8, 34)
-37%
49.2 (22, 27.2)
-4%
33.6 (16.4, 17.2)
29%
44.8 (21.2, 23.6)
5%
Response Time Black / White *
17.6 (6.8, 10.8)
30.4 (10.8, 19.6)
-73%
32.2 (19.2, 13.2)
-83%
24 (12.4, 11.6)
-36%
27.6 (15.6, 12)
-57%
PWM Frequency
200 (99)
2404 (50)
1102%
201.6 (99)
1%
Screen
-9%
-23%
-13%
0%
Brightness middle
574
422
-26%
532
-7%
338
-41%
381
-34%
Brightness
540
395
-27%
513
-5%
315
-42%
375
-31%
Brightness Distribution
86
90
5%
90
5%
88
2%
94
9%
Black Level *
0.36
0.27
25%
0.41
-14%
0.43
-19%
0.24
33%
Contrast
1594
1563
-2%
1298
-19%
786
-51%
1588
0%
Colorchecker DeltaE2000 *
4.7
4.7
-0%
6.88
-46%
4
15%
4.6
2%
Colorchecker DeltaE2000 max. *
8.8
10
-14%
12.65
-44%
7.9
10%
8.5
3%
Colorchecker DeltaE2000 calibrated *
1.4
2
-43%
2.52
-80%
1.7
-21%
1.2
14%
Greyscale DeltaE2000 *
7.2
6.4
11%
10.5
-46%
6.2
14%
5.1
29%
Gamma
2.04 108%
2.12 104%
1.98 111%
2.13 103%
2.52 87%
CCT
6886 94%
7106 91%
7394 88%
6787 96%
7052 92%
Color Space (Percent of AdobeRGB 1998)
73.8
59.5
-19%
74.1
0%
68.1
-8%
60.7
-18%
Color Space (Percent of sRGB)
99.4
91.5
-8%
99.7
0%
97.8
-2%
95.7
-4%
Total Average (Program / Settings)
161% / 64%
-26% / -24%
-9% / -12%
-13% / -4%

* ... smaller is better

The spec sheet lists a 90% coverage of the DCI P3 color gamut. As per usual on Lenovo devices, you cannot adjust the color space and there are no different color profiles, either, which means you are limited to the P3 gamut. We can detect high deviations for the grayscale and the colors out of the box, both compared to the sRGB as well as the P3 color gamut.

CalMAN Grayscale (target color space sRGB)
CalMAN Grayscale (target color space sRGB)
CalMAN Saturation Sweeps (target color space sRGB)
CalMAN Saturation Sweeps (target color space sRGB)
CalMAN ColorChecker (target color space sRGB)
CalMAN ColorChecker (target color space sRGB)
CalMAN Grayscale (target color space P3)
CalMAN Grayscale (target color space P3)
CalMAN Saturation Sweeps (target color space P3)
CalMAN Saturation Sweeps (target color space P3)
CalMAN ColorChecker (target color space P3)
CalMAN ColorChecker (target color space P3)

Our measurements with the professional CalMAN software and the spectrophotometer X-Rite i1 Pro 2 also reveal a slight color cast towards blue/red. You will definitely have to calibrate the panel (our calibrated profile is also available to download for free in the box above) to utilize the full potential of the screen. After the calibration, the high deviations as well as the color cast are gone completely. There are still some outliers in the Colorchecker, which surpass the important mark of 3, but the panel is still suited for picture/video editing in the P3 gamut.

CalMAN Grayscale calibrated (target color space P3)
CalMAN Grayscale calibrated (target color space P3)
CalMAN Saturation Sweeps calibrated (target color space P3)
CalMAN Saturation Sweeps calibrated (target color space P3)
CalMAN ColorChecker calibrated (target color space P3)
CalMAN ColorChecker calibrated (target color space P3)

As we have mentioned before, Lenovo does not offer any method to adjust the color space. This is not ideal, because the targeted P3 gamut is only covered by 86.8% according to CalMAN (Lenovo advertises 90%).

The panel also supports HDR (HDR 400, DolbyVision), but you have to activate it manually in the Windows settings. After that, contents are shown correctly, for example when you watch YouTube videos or Netflix. You can also see the difference on the screen, but it is hard to show without a corresponding HDR screen. This means there is a certain HDR effect, but you cannot compare the result with a HDR TV due to the comparatively low maximum brightness.

vs. sRGB: 99.4 % (Argyll 3D comparison)
vs. sRGB: 99.4 % (Argyll 3D comparison)
vs. AdobeRGB: 73.8 % (Argyll 3D comparison)
vs. AdobeRGB: 73.8 % (Argyll 3D comparison)
vs. P3: 86.8 % (CalMAN 2D comparison)
vs. P3: 86.8 % (CalMAN 2D comparison)

Display Response Times

Display response times show how fast the screen is able to change from one color to the next. Slow response times can lead to afterimages and can cause moving objects to appear blurry (ghosting). Gamers of fast-paced 3D titles should pay special attention to fast response times.
       Response Time Black to White
17.6 ms ... rise ↗ and fall ↘ combined↗ 6.8 ms rise
↘ 10.8 ms fall
The screen shows good response rates in our tests, but may be too slow for competitive gamers.
In comparison, all tested devices range from 0.8 (minimum) to 240 (maximum) ms. » 21 % of all devices are better.
This means that the measured response time is better than the average of all tested devices (24.6 ms).
       Response Time 50% Grey to 80% Grey
47.2 ms ... rise ↗ and fall ↘ combined↗ 20.4 ms rise
↘ 26.8 ms fall
The screen shows slow response rates in our tests and will be unsatisfactory for gamers.
In comparison, all tested devices range from 0.9 (minimum) to 636 (maximum) ms. » 76 % of all devices are better.
This means that the measured response time is worse than the average of all tested devices (39 ms).

Compared to matte panels, the glossy 4K screen is obviously worse outdoors, despite the higher luminance. You are always dealing with strong reflections in bright environments and you should always align the screen to avoid direct light sources or bright surfaces in the background. There is no criticism for the viewing angle stability of the IPS screen, though.

In the sun
In the sun
In the sun
In the sun
Viewing angle stability
Viewing angle stability

Battery Runtime - ThinkPad with 4K panel consumes much more power

The 4K panel of the ThinkPad X1 Carbon requires much more power than the LowPower 1080p screen or even the WQHD panel, which is still available for the ThinkPad X1 Carbon G8 outside the EMEA region. Compared to the 1080p model, the battery runtime in our Wi-Fi test drops by around 30% (7h vs. 10h) and the difference is even bigger when we repeat the test with the maximum display brightness (4:22h vs. 8:19h). Our video test runs for around 7.5 hours at an adjusted luminance of 150 nits.

The battery runtime is not really bad, and it will probably be sufficient for some usage scenarios. You should definitely consider how often you really use the X1 Carbon on battery before you purchase the device.

Lenovo ThinkPad X1 Carbon 2020-20U9003BGE
i7-10510U, UHD Graphics 620, 51 Wh, 3840x2160
Lenovo ThinkPad X1 Carbon 2020-20UAS04T00
i7-10510U, UHD Graphics 620, 51 Wh, 1920x1080
Lenovo ThinkPad X1 Carbon G7 20R1-000YUS
i7-10510U, UHD Graphics 620, 51 Wh, 3840x2160
Lenovo ThinkPad X1 Carbon 2019-20QE000VGE
i7-8665U, UHD Graphics 620, 51 Wh, 2560x1440
Lenovo ThinkPad X1 Carbon 2019-20QES01L00
i7-8565U, UHD Graphics 620, 51 Wh, 1920x1080
Average of class Office
 
Battery Runtime
57%
42%
24%
43%
0%
H.264
450
770
71%
586
30%
688
53%
445 (139 - 882, n=200)
-1%
WiFi v1.3
422
604
43%
598
42%
493
17%
562
33%
427 (105 - 1124, n=400)
1%
Battery Runtime
NBC WiFi Websurfing Battery Test 1.3 (Edge 83.0.478.64)
7h 02min
NBC WiFi Websurfing Battery Test 1.3 max Brightness (Edge 83.0.478.64)
4h 33min
Big Buck Bunny H.264 1080p
7h 30min

Pros

+ very compact and light
+ good system performance
+ quiet fans
+ very good speakers
+ comprehensive warranty options
+ integrated LTE
+ Wi-Fi 6
+ still a very good keyboard...

Cons

- ... but worse compared to other ThinkPads
- 4K display has a glossy surface and suffers from PWM
- no SD reader
- very limited maintenance
- LAN only via (included) adapter

Verdict - 4K screen has some drawbacks

In review: Lenovo ThinkPad X1 Carbon 2020. Test model courtesy of Lenovo Germany.
In review: Lenovo ThinkPad X1 Carbon 2020. Test model courtesy of Lenovo Germany.

Lenovo does not offer the matte WQHD panel for the ThinkPad X1 Carbon G8 in all regions, so you have to upgrade from the 1080p to the 4K screen if you want a higher resolution panel. The first impression of the picture quality is very good with rich colors, high contrast, and bright illumination.

However, there are two limitation. First of all, the screen is glossy. This obviously improves the subjective picture impression, but you will be quickly annoyed by the reflections on the screen if you often use the laptop on the road. The biggest problem is the PWM flickering if you do not use the maximum brightness. We detect a very low frequency of just 200 Hz, so some users will most likely have problems (like headaches, for example). This means the panel is hardly suited for longer working sessions and we can only recommend it if you know that you are not sensitive to PWM flickering. Otherwise, you should definitely test the model and check if you notice any problems.

The 4K panel of the ThinkPad X1 Carbon uses PWM at a very low frequency, so it is not a good option for many users. 

The high-resolution panel also affects the battery runtime. All in all, the standard matte 1080p screen is a better fit for a business laptop, even though there is still the issue with Lenovo's panel lottery (we reported). Otherwise, there are the same advantages/disadvantages we have described in the review of the 1080p model.

Lenovo ThinkPad X1 Carbon 2020-20U9003BGE - 07/21/2020 v7
Andreas Osthoff

Chassis
88 / 98 → 90%
Keyboard
90%
Pointing Device
89%
Connectivity
74 / 80 → 93%
Weight
74 / 20-75 → 98%
Battery
73%
Display
69%
Games Performance
52 / 78 → 66%
Application Performance
89 / 95 → 94%
Temperature
89%
Noise
98%
Audio
74%
Camera
38 / 85 → 45%
Average
77%
86%
Office - Weighted Average

Pricecompare

Read all 6 comments / answer
static version load dynamic
Loading Comments
Comment on this article
Please share our article, every link counts!
> Notebook / Laptop Reviews and News > Reviews > Lenovo ThinkPad X1 Carbon 2020 Business-Laptop Review: 4K display costs battery runtime
Andreas Osthoff, 2020-07-24 (Update: 2020-07-24)
Andreas Osthoff
Editor of the original article: Andreas Osthoff - Managing Editor Business Notebooks
I grew up with computers and modern consumer electronics. I am interested in the technology since I had my first computer, a Commodore C64, and started building my own PCs after that. My focus here at Notebookcheck is the business segment including mobile workstations, but I also like to test new mobile devices. It is always a great experience to review and compare new products. My free time is filled with a lot of sports, in the summer mainly on my bike.