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Dell XPS 15 2-in-1 (9575) Review: Kaby Lake-G Hits the Road

Author: Ken Addison
Subject: Mobile
Manufacturer: Dell

CPU and Storage Performance

The Core i7-8705G falls into a strange place in Intel's current mobile CPU lineup. Kaby Lake-G is sandwiched between the 15W quad-core U-series processors and the 45W six core H-series CPUs. As a result, we are comparing the XPS 15 2-in-1 to a variety of 8th generation U-series equipped notebooks, the Ryzen 5 2500U, and the Core i7-8809G found in the Intel Hades Canyon NUC.

Cinebench R15

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In Cinebench R15, the Dell XPS 15 2-in-1 manages to slightly beat our previous performance winner in mobile testing, the XPS 13 9370.

Additionally, there is a significant performance gap of over 15% between the Kaby Lake-G powered Hades Canyon NUC and the XPS 15 2-in-1.

Handbrake 1.0.7

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Handbrake shows a 10% encode time advantage for the XPS 15 2-in-1 over the XPS 13 9370 but falls 15% short of the encoding speed of the Hades Canyon NUC.

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Charting the CPU frequency during the Handbrake encode points out an interesting dynamic of the XPS 15 2-in-1. The clock speed seems to be ramping up and down in a sawtooth-like pattern to prevent thermal issues.

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Looking at the Processor Power data from this same encode, we see the same sawtooth pattern as the processor hits the 50W maximum TDP, and then downclocks, only to start the pattern all over again.

Regardless, the average clock speed of around 3.2 GHz provides a significant advantage over the Kaby Lake Refresh-based XPS 13 9370.

PCMark 10

PCMark 10 Extended is a benchmarking suite that aims to emulate several different usage scenarios ranging from basic productivity to mixed workloads, as well as light gaming and to applications for creative professionals like photo and video editing.

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The AMD Vega-powered graphics of the Dell XPS 15 2-in-1 allow it to slightly outperforming the GTX 1050-equipped Surface Book 2. However, in the more CPU-bound Essentials test, the XPS 13 9370 manages to pull an over 5% lead.

Overall, the CPU performance of the i7-8705G seems to be much closer to the 15W Kaby Lake Refresh quad-core CPUs than we would have expected. Despite sharing a CPU architecture (Kaby Lake), and having an extra 30W of power draw in the Dell XPS 15 2-in-1 design, the performance benefits don't seem to scale on purely CPU-bound tasks.

Storage Performance

Storage performance has been disappointing with the last few notebooks we have looked at recently. Both the Microsoft Surface Book 2 and the Dell XPS 13 9370 seem to be employing write speed throttling, artificially limiting their high-end SSDs to sometimes embarrassing rates in the name of power consumption.

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SSD speeds aren't a concern with the XPS 15 2-in-1 though. The SK Hynix PC401 SSD provides over 1.0 GB/s sequential write speeds, and over 2.5 GB/s sequential read speeds.

While not the absolute peak of modern NVMe performance, the 1.0 GB/s write speeds are suitable for notebook applications where it's difficult to generate the data fast enough to saturate the SSD in the first place.

Video News


June 1, 2018 | 09:51 AM - Posted by Rich R (not verified)

Received mine on Wednesday and needed to update the drivers on several items.

The machine could not auto-rotate the screen this was one of several out-of-date Intel drivers that can be updated from Dell support.

The Vega M gpu was reported as Generic VGA, and I didn't see anything on the Dell support pages to correct this. The ARK page for this CPU however did have the AMD Vega driver though, so I installed them from there.

Now I'm just curious to find out how to ensure the graphics tasks are actually being conducted by the Vega M GPU and hot the Intel HD xxx GPU, which are both active.

June 1, 2018 | 10:52 AM - Posted by Chaitanya (not verified)

Really hate that Dell has decide to solder RAM and go route of removing SD card slot and full sized USB A port.

June 1, 2018 | 11:43 AM - Posted by ReallyTooAppleCrappleLike (not verified)

So "100% AdobeRGB coverage" and more graphics software testing please.

"In this case, we have two Thunderbolt 3 ports (providing full x4 throughput), as well as two USB 3.1 Gen 2 ports."

x4 of what? PCIe 2.0 or PCIe 3.0 and the Kaby lage G version gets the Soldered RAM while the non G versions get the upgradable RAM SODIMMS. I'll bet that the TB3 ports(Type-C) and the USB 3.1 gen 2 ports(Type-C also) are one and the same ports so more adaptor profits for Dell(very Apple Like). And forget that USB Type-C to USB Type-A adaptor as that can be replaced with a Type-C to Gigabit Ethernet adaptor option for those that use wired connections.

This is just more like Apple(not very user upgradable) and less like non Apple laptops(more upgradable). And I can not wait for AMD's Mobile Vega(Real Vega) to appear in a non Intel(Sort of "Vega" semi-custom) True AMD Zen/Vega option. And no one reviewer appears to have the jewels to see if that Semi-Custom "Vega" in the Kaby Lake G has that working HBCC IP. That Vega HBCC IP that can make use of the HBM2 as High Bandwidth Cache for the GPU with the ability to have more Virtual VRAM swapped out to and from regular system DRAM for non gaming graphics workloads where the user would want very high resolution images that may take up more than only 4GB of VRAM.

I'm Really not liking some reviewers who do not provide close up shots of the Ports on a laptop along with some better all around images of the laptop and those MagLev Butterfly like switches are they exactily like Apple's Butterfly IP that's going to get Apple some Class Action Treatment what with the issues they are having with that.

I want a Raven Ridge APU laptop with some Vega Discrete mobile Options with 4GB of HBM2 and that HBCC/HBC IP that actually works for allowing the user to have the HBM2 acting like a GPU Cache to a much larger pool of Virtual VRAM out on regular system DRAM.

June 5, 2018 | 09:07 AM - Posted by Rich R (not verified)

The Type-C ports on the left are thunderbolt. The rearmost having the power symbol as well. The two on the right are the USB3 ports. The power brick can be plugged into any of the 4.

I would have liked to have one Type-A port so I don't have to use the dongle to plug in the logitech universal adaptor. (I really don't like trackpads so a marathon mouse is always in my kit.)

June 1, 2018 | 11:53 AM - Posted by Stef (not verified)

Good news: It's as fast as a mobile GTX 1050
Bad news: It have half the mileage than a GTX 1050 system with the same battery, really poor battery life but something which was expected given Vega's power efficiency

June 1, 2018 | 01:48 PM - Posted by Rocky1234 (not verified)

Total no go first off on the cheapest model 128GB SSD only once windows is installed and of coarse the Dell recovery you are left with very little room. The second thing going from 128GB to 256GB is like $200 extra are they on glue. Third thing non expandable memory so you are stuck with whatever the unit came with. I hope this is not a trend but then again if the likes of Del and Apple and MS get away with it then this will become the norm for every company to do in the future.

June 7, 2018 | 03:35 PM - Posted by ~wizpig64 (not verified)

This is the first time I've seen the review terms and disclosure, I think it's a great idea.

June 7, 2018 | 06:47 PM - Posted by Jeremy Hellstrom

Thank you.

June 28, 2018 | 01:07 PM - Posted by Jared E. (not verified)

I am looking at the XPS 15 (9575) and the XPS 15 (9570). do either of these support miracasting with the killer wireless hardware in them? Either the 1535 or the 1435 series? Dell has no support info on these 2 machines and Killer Networks doesn't either? I find things in forums, but not for these 2 machines? Any help would be great!

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