Dell XPS 15 9550 (i7, 512GB, UHD) InfinityEdge Notebook Review

The display frame of the UHD touch version differs a bit from the matte FHD version. While the FHD TFT has a 5 mm thin plastic bezel with a surrounding plastic ring, the surface of the touch panel extends to the surrounding plastic ring. It is once again not a rubber lip, but plastic, which sits on the base unit when the lid is closed.

Grease is another persistent topic, because the soft-touch carbon surface is pretty prone to it. Unfortunately, a cleaning cloth will not remove those glossy stains. We tried it with some butter: You can polish them away dry or wet, but the result is marked by streaks and polishing traces. This means the expensive premium notebook becomes unsightly if you do not clean it extensively.

Dell targets professional users with the 4K panel, which is only available as a touchscreen. Photoshop tools or In-Design can utilize the 3840x2160 pixels. Older tools and Windows can sometimes still have scaling issues (power settings are always opened as a tiny window). But you don't want to go back to Full HD once you have worked with the 4K screen from Sharp.

It is an IGZO-TFT similar to the current XPS 13 4K Touch (SHP1421 LQ133Y1). It is a type of IPS panel where the amorphous silicon (aSi-TFT) is replaced with indium-gallium-zinc-oxide. This increases the electron mobility by multiple times and results in faster response times. At least in theory, because our measured response times are not what gamers would expect at 35 and 58 milliseconds, respectively (XPS 13 QHD 30 and 40).

We can confirm the advertised panel specs (WLED 330 cd/m², 1000:1), luminance and contrast are on this level. There is no noteworthy backlight bleeding. Buyers of the UHD version report a red/purple hue, which is particularly visible with black and blue pictures. We also noticed this phenomenon for the FHD version, but similar to the UHD panel only from very wide angles from the side or above. Subjectively, we did not think that it was a big issue for our two test models, but the intensity seems to differ depending on the batch. There are readers' comments/pictures that report a massive distraction. This was not the case for our SHARP LQ156D1JX01.

The mentioned combination of a 6700HQ and NVMe-SSD should also be sufficient for demanding calculations and massive data transfers. Users should be able to expect that for 2,000 Euros (~$2195) though, especially since you can already get the 6700HQ + GTX 960M for around 1,300 Euros (~$1426) in other good notebooks like the Acer Aspire V Nitro Black Edition VN7-792G-74Q4, for example.

The XPS 15 with the i5-6300HQ obviously comes to mind, which only executed the Cinebench R15 loop at 2.8 GHz (Single and Multi), which shows a bad utilization of the single-core Turbo (-15%). The i5 also throttled to 1.6 GHz on battery power, which was unfortunately not lifted when the PSU was attached (only after standby or restart). Dell is already working on a fix according to the manufacturer.

So how does the i7-6700HQ perform, which should be able to hit 3.5 GHz with the Turbo (single-core)? We can see a very agile processor, which not only beats the Haswell 4870HQ of the Apple MacBook Pro Retina 15 but also the identical 6700HQ in the Aspire V Nitro Black Edition VN7-792G-74Q4 (-5%). This is the case in all Cinebench Single-Tests. Our XPS is on par with the Nitro Black Edition in the Multi-Test; our tools show 3.1 GHz.

The i7 runs at the nominal clock of 2.6 GHz on battery power. Unfortunate, but still better than the i5 version with its throttled 1.6 GHz. The transition to mains (attach the connector) is, however, a bit bumpy. We have no other way to describe the following 1.6/1.7 GHz in this case. This is not related to temperature limits, because the throttled clock is quickly increased to 3.1 GHz after the stress test. More information about the stress test is available in the section "Emissions."

The clocks on battery power only change after the BIOS update to 1.1.14. The R15 Multi now runs at 3.1 until the battery is empty! This is the case after around one hour. Officially, the BIOS update only covers the NVMe sleep mode (should improve battery runtimes), but we only noticed an unlimited Turbo Boost. The return to the PSU is now as it should be as well: 800 MHz for one second, after that 3.1 GHz. The clock drops to 800 MHz after you pull the plug, just to climb back to 3.1 GHz step by step within 20 seconds.

While the HD Graphics 530 of the processor handles simple tasks, the GeForce GTX 960M with 2 GB GDDR5-VRAM takes care of games or hardware-accelerated applications. The core is based on the GM107 chip (Maxwell) with 640 shaders and a 128-bit memory interface. The GeForce races up to 1,188 MHz on mains, even under sustained loads (FurMark GPU stress test).

The GPU Boost of 1,188 MHz is always fully utilized on mains power, even during the stress test and simultaneous stress for the CPU. The temperature is 87 °C in this case. The GPU is repeatedly slowed-down to 850 MHz in the stress test on battery power, but it is raised back to 1,188 MHz in intervals of 5 seconds. The temperature of the Nvidia chip drops to 68-75 °C in this case. The GPU is favored in the temperature table, which means the GPU Boost is raised first, before the CPU clock of 900 MHz is slightly increased to stay at one point, which does not create too much heat. This point is at 988 MHz (on average), for example, in the stress test – also see section "Emissions." 

The situation is good for the 3DMarks and the scores are, as expected, on par with other GTX 960M notebooks. The XPS 15 i5 only falls behind in the Physics scores. Other GTX 960M notebooks are just beaten (ZenBook Pro, MSI PE60) or they are slightly faster (AS V Nitro VN7-792G, IdeaPad Y50-70). All in all, the performance utilization of the GTX is very good and on par with the best rivals. Is this also the case in real games?

The system noise of the XPS 15 knows three different levels: Silent, high and annoying. The silent idle operation is shown by the green line in the chart. The noise during the stress test and gaming (3DMark06) hardly differs; it results in the highest fan speed and is already quite loud at 45 dB(A), but it is still reasonable considering the performance of the system. We also showed a CB R15 loop, which is more tolerable at 41 dB(A).

The i5 model showed a different behavior, because the load average was not identical to the maximum load. Games should therefore result in a lower noise on the i5 XPS. 

Three levels do not mean that there aren't any graduations. The two fans will slowly increase and decrease their speed. The cooling solution will run for quite a long time after periods of load at 33.4 dB(A), so the user might be confronted with a fan that is always audible depending on the scenario. We did not notice coil whine, even when the fans were deactivated.

The review unit is equipped with an 84-Wh battery, which replaces the 54-Wh module of the i5 model but occupies the space of the 2.5-inch SATA-HDD. The overall runtimes are disappointing, because they fall just behind the i5 hybrid model (54 Wh) in every test. We did not expect anything else due to the much higher power consumption though. The less expensive Nitro Black Edition VN7-792G is much more frugal while idling and manages 254 minutes (-18%) in the Wi-Fi test with its much smaller battery (52 Wh). The idle and the video tests show constant results, so we can rule out an incorrect measurement.

Contrary to all the promises, BIOS 1.1.14 did not improve the runtimes. 8:32 hours while idling, 5:10 in the Wi-Fi test and 5:00 during video playback (H.264). Those runtimes are even a couple of minutes shorter, but the results are within normal measuring tolerances. An interesting aspect is the significantly shorter runtime under load with 1:14 hours instead of the 2:05 hours with BIOS 1.1.05. It confirms that BIOS 1.1.14 enables higher clocks on battery power.

One bug after another? After the entry-level XPS 15 (FHD/i5/hybrid) could not meet the high expectations, we were careful with the more expensive and better-equipped XPS 15 with a UHD panel, NVMe-SSD and Core i7. Who wants to spend more than 2,000 Euros (~$2195) to be faced with CPU throttling, low runtimes or even PWM flickering? But we can soothe concerns after this review update – at least some of them. The CPU and GTX 960M can utilize their full performance and there is no PWM flickering, not even at the lowest brightness levels. The runtimes are disappointing though; they are still shorter compared to the 54-Wh FHD model even after the BIOS update 1.1.14 (NVMe SleepBug).

The 6700HQ lives up to its name and can even beat the Aspire Nitro Black Edition in the Cinebench tests on mains. The i7 can also utilize its Boost (3.1 GHz) on battery power. The latest BIOS is important; the XPS 15 was stuck at 2.6 GHz ex-works (BIOS Rev. 1.1.05) and had throttling issues during the transition to mains.

The lack of a mechanical drive also removes the annoying noises that affected microphone recordings of the entry-level XPS 15. One problem is the unsightly soft-touch surface of the palm rest. Now, after two weeks with both XPS 15 versions, we can see the whole splendor of hardly removable stains (also on the touchpad).

The Sharp UHD panel is one of the best of its kind, which is supported by the 89% AdobeRGB coverage and the very good results after calibration in particular. The color hue from the side with dark or brighter surfaces is a minor issue in our opinion; at least it would not prevent us from a purchase. 

We can repeat our results from the first XPS 15 review when we look at the advantages: Excellent build quality combined with good maintainability and very compact dimensions. The cooling solution acts reasonably and performance fans won't be disappointed after the BIOS update. The good sound from the speakers and the future-proof Thunderbolt 3 complete the package.

All in all – if we ignore the initial bugs and confusion – the XPS 15 UHD is a great working tool with limited drawbacks. If you want perfection in every regard, you will already be disappointed with the webcam, but the runtimes will blow away any sympathies. If the contra points are not important for you, then you get a very good notebook in terms of the other aspects, which can keep up with the Apple MacBook Pro Retina 15 2015.