Dell Latitude 7390 (Core i7-8650U, Touchscreen) Laptop Review

The display panel has only changed slightly since last month’s model. Today’s unit still features a 13.3-inch 1920x1080 IPS matte display (166 PPI), and subjectively, it appears almost identical to that of the previous 7390 we reviewed. But there is one major difference: it’s also a touchscreen. Whereas in the past, Dell has labeled their reflection-diffusing touchscreens “anti-glare”, they are still most certainly glossy—but this screen is not. It is exactly the same in appearance to any other standard, non-touch, matte-finished panel, but it is in fact a touchscreen—an accomplishment which effectively dispels the biggest criticism with the touchscreens of yore. Lenovo has something similar in their X1 Carbon, but the Latitude’s implementation is even more subtle. The specific technology being employed here is called "Embedded Touch" anti-glare.

The panel does not employ PWM at any brightness level. Response times are on the slower side, but this is nothing new for notebooks in this class. In spite of its touchscreen, the display is easily viewable outdoors thanks to its authentically matte finish and reasonable brightness/contrast levels. The IPS panel accommodates wide viewing angles.

The Core i7-8650U is a quad-core SoC carrying operating frequencies of 1.9 GHz (base) all the way up to 4.2 GHz (max turbo). Given the constraints of its 15 W TDP and the accompanying high temperatures, it isn’t possible to maintain such high frequencies for more than a very short period of time. In light of this fact, is it possible to justify the higher cost of the Core i7 versus the i5 of last month’s model?

Before we directly answer this question, let’s first take a look at performance of the Latitude’s i7-8650U versus that of other machines. Judging by a total of 7 samples (at the time of this writing), the Latitude 7390 is slightly ahead of the average across all benchmarks. That’s good news since we’ve found it difficult to justify the purchase of an 8^th-gen i7 in many other laptops after witnessing disappointing sustained performance scores. That isn’t to say that performance of these chips is underwhelming—it’s actually extremely good considering their power consumption—but the Core i5 SoCs manage such impressive scores already that the jump to an i7 is just very difficult to recommend.

Thanks to the jump from conventional M.2 storage to an NVMe drive (specifically, a Samsung PM961 256 GB solid-state drive), the Latitude 7390 musters system performance scores some 8 to 12 percent above last month’s unit, and instead much closer to last year’s Latitude 7380 (which featured the same SSD). Subjectively speaking, we certainly have no complaints with regard to the machine’s performance, which was fluid and zippy throughout our time with it.

Last month’s SK Hynix SC311 can’t hold a candle to the Samsung PM961 in today’s test unit—but likewise, the PM961 is easily outclassed by the PM981 installed in the ThinkPad X1 Carbon. Still, an AS SSD score of 2215 (spurred by sequential read/write speeds of 1760.62 MB/s and 830 MB/s) is nothing embarrassing, and most users would hardly even notice the difference moving farther beyond these speeds in everyday usage scenarios.

Unsurprisingly, the Latitude 7390 can’t maintain high turbo clock rates for longer than a short period of time in our synthetic stress tests. This limitation is hardly unique to the Latitude, however, as we’ve witnessed similar behavior from practically every 8^th-generation Intel-powered device we’ve tested. Although max clock rates of 4.2 GHz are never even really reached under heavy loads, the laptop is at least capable of maintaining 2.9 GHz stably across all four cores—an achievement that renders it far faster than its 7^th-generation predecessors in any CPU-intensive activity. You can see in our graphs below that as the demand on the CPU suddenly starts, we see a spike in CPU Package Power (to some 44 W) and initial core clock rates (to around 3.8 GHz), but just seconds later the power consumption begins dropping rather sharply down to 22 W, where it remains.

Full GPU stress produces stable clock rates of 1000 MHz from the GPU (1150 MHz is the maximum specified for the chip); temperatures remain stable at around 76 °C.

Combined CPU and GPU stress sees the system favoring GPU over CPU clock rates. The former holds firm at 950 MHz and the latter drops all the way to 1.5 GHz, where it stays permanently (temperatures, meanwhile, hover around the 77 – 78 °C mark). That qualifies as CPU throttling since it’s below the base frequency of 1.9 GHz—though it’s not likely that such a scenario would apply during real-world usage.

Power consumption has only risen slightly over the Core i5 model; a mere difference of 0.3 W while idling (average) and 0.2 W under load. We didn’t see any spikes into the 60 W range thing time around, but we’ll discover in the next section whether any of these observations affect battery life.