Dell XPS 15 Haswell Edition: QHD+ with a Refined Design
by Jarred Walton on March 6, 2014 7:00 AM ESTDell XPS 15: Battery Life
Our final set of tests is for battery life, and here again we have a change or two to make. I did run our 2013 battery tests, but for 2014 I’ve made some changes. First, our “Heavy” test will now use the Windows Video app to play back a 1080p MP4 movie – the use of MKV files basically resulted in lower battery life by a fairly large margin, and MP4 files are readily available. I’m also considering dumping the “Moderate” workload and just sticking with Light and Heavy testing, as well as including approximate gaming battery life. There’s this mentality of “more information is always better”, but by the same token more information and testing means more time and thus less timely reviews. In general, our Medium battery life results have been pretty consistent about falling half way between our Light and Heavy tests, and with the newly modified Heavy test it’s just one extra benchmark with questionable value.
With that said, we continue to test with LCD backlighting set to 200 nits, WiFi is enabled, and earbuds are connected to the headphone jack. For the XPS 15 QHD+ display, 200 nits ended up being at exactly 50% brightness, which makes things easy on us. I do like that Dell has relatively consistent steps between backlight levels of around 35 nits per 10%. Many laptops that I’ve used in the past have been far less granular, sometimes going from 300 nits at 100% to 200 nits at 90% and then 10 nits intervals from there down to 0%.
Thanks in a large part to the 91Wh battery, the XPS 15 is able to place quite far up our battery life charts in terms of raw unplugged time. It’s not quite so awesome when we look at the normalized Min/Wh figures, but while that can be useful information at the end of the day people are going to be using the battery they get with this laptop. We measured nine hours of battery life in our light workload, nearly 6.5 hours in our moderate workload, and around 4.5 hours in our heavy workload.
Interestingly, our new Heavy test using the Video app with a lower bitrate 1080p MP4 results in battery life that’s basically the same as our previous Medium testing – so with Video, playing a fullscreen MP4 while streaming 1MBps and loading Internet pages every ten seconds isn’t really any more taxing than playing back an MP3 while surfing the web. It appears Microsoft's Video app can scale content without incurring a power penalty, whereas when I was using Media Player Classic previously higher resolution displays often did worse (e.g. look at the XPS 15 results above).
Trying to game off the mains is a different matter, however, and even with a relatively large battery the XPS 15 only manages less than two hours while running Skyrim. (If you’re wondering, for testing gaming battery life, we use the Balanced power profile with the GPU set to “Prefer Maximum Performance”. Then we load up our Skyrim save in the town of Whiterun and let the system run until the battery is drained. The camera begins to pan around the character so it’s at least moderately demanding, though other games are certainly more so.)
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Luscious - Thursday, March 6, 2014 - link
My big issue with this notebook (and other big box notebook manufacturers) is Dell's insistence on pushing Windows 8.1 rather than offering consumers a choice of Windows 7. I'd be happy if Dell offered just the OS drivers for this on their support website, since I can install the OS myself, but they don't. It's good that boutique builders like Eurocom continue to offer Windows 7 with their notebooks.JarredWalton - Thursday, March 6, 2014 - link
Meh. Windows 8.1 with Classic Start or similar bypasses 99% of the problems I have with Windows 8 (Modern). Plus, the boot times are really improved, and probably some other nice things as well. It's not perfect by any means, but I don't care enough to try going back to Win7 on a laptop that ships with Win8. If you're in a corporate environment, though, I can see this being a bigger issue.jphughan - Friday, March 7, 2014 - link
Windows 7 drivers are available by looking under the essentially identical Precision M3800 page. The only exception is NFC, which doesn't exist on the M3800., but the 8.1 driver from the XPS page may work on 7.unni - Thursday, March 6, 2014 - link
I can confirm 100% that the throttling happens only if the laptop is at an angle. As long as it is on a level surface, eveything is fine. I have played Battlefield 4 for 30 mins at 30-fps when the laptop was on a table. As soon as I change the angle of the laptop, throttling kicks in within 1-2 minutes even when there is nothing blocking the vents. This is a strange behaviour and doesn't seem to have anything to do with temperature either. I had Dell replace the motherboard and apply new thermal paste. The issue was still there. As part of the trouble shooting, I had to completely restore it to how it came from factory. I didn't update any drivers except BIOS. Now, BF4 runs at 30fps without any throttling. Also, one user had recommended in Dell forum to use NVidia Inspector and limit the FPS to 30 (if you are on the latest drivers). Strangely, that works as well.unni - Thursday, March 6, 2014 - link
The line"I have played Battlefield 4 for 30 mins at 30-fps when the laptop was on a table."
should be
"I have played Battlefield 4 for 30 mins at 30-"50 fps when the laptop was on a table.
JarredWalton - Thursday, March 6, 2014 - link
I can confirm 100% that throttling happens even when the laptops are on a flat surface. Sorry, but I've tried lots of things when the throttling has occurred, and none of them fixed the problem (unless I rebooted, but that wasn't don enough to actually notice until yesterday).unni - Friday, March 7, 2014 - link
I guess there are differences between our machines then. Mine is the full SSD one. I don't have to reboot either. All I need is to quit and relaunch the game. Throttling will be gone.xTRICKYxx - Friday, March 7, 2014 - link
Once throttling occurs the first time, the chances of throttling happening again increases dramatically.xTRICKYxx - Friday, March 7, 2014 - link
Disabling turbo boost or downloading throttle stop would probably fix this entirely.Wolfpup - Thursday, March 6, 2014 - link
I've had much better luck with Dell notebooks than anything else, but I'm still picking an Alienware 17 or the like over this...