Using DeX with the Galaxy Note 9: how are the performance and battery life?

Using DeX with the Galaxy Note 9: how are the performance and battery life?
Samsung's desktop experience (DeX) has been a thing since the launch of the Galaxy S8. However, up until now, we had to use a separate DeX Station or DeX Pad dock in order to enter the desktop mode — the dock was mainly required for its internal fan that kept the device cool as well as feeding power to the phone while it was working in DeX mode.

The Samsung Galaxy Note 9 is a true powerhouse, packing the latest and greatest Qualcomm Snapdragon 845 under its hood and 6 GB of RAM to complement it. All of this is powered by a 4,000 mAh battery, which is 21% more capacity than the cell in the Note 8. To top it off, Sammy added a new "water-carbon" cooling system with a huge pipe and promised that the phone would run cool even under intense loads.

All of this led to the ability to run the Samsung DeX desktop experience with nothing but a USB-to-HDMI cable.

Now, we have some questions

How easy is the setup? Does the Galaxy Note 9 heat up if we put it through an intense DeX session? Does the battery drain too fast for any work to be done?

Setting up Note 9 DeX with a generic HDMI-to-USB Type C cable

The setup is easy and straightforward. Find an HDMI to USB Type C cable (Samsung recommends using their own brand accessory, but we used a generic one), plug it in the monitor and phone. DeX will begin the startup process instantly.

Now, we did notice that it takes quite a while to boot up. Unlike the DeX Station, which worked almost instantly, the Note 9 took its time to power up the monitor when we used a cable. However, this might work faster with a Samsung-brand accessory.

You can pair a Bluetooth keyboard and mouse of choice, either before you enter DeX or through the DeX settings once you are in there. If you don't have any peripherals at all attached right now, the Note 9 itself transforms into a touchpad for mouse control. Tapping on a text field will pop up the phone's virtual keyboard, so you can use that to write.

Productivity and speed

We noticed absolutely no loss of productivity power compared to our previous experiences with dedicated DeX docks. The Note 9 was capable of keeping multiple windows open without a hitch.

We opened up Chrome with two tabs of loaded, a YouTube window with a 1080p video playing in the background, the Play Store to download a heavy game (PUBG), the game itself, and a window of Facebook for good measure.

The Note 9 was able to keep all of them open and running without a hitch. Granted, the Facebook app and PUBG will go in a "frozen" state as soon as you click away from their window, but focusing on them again will resume the work where you left off.

Power drain and heat

All of this is well and good, but how much of a toll does this take on the battery? After all, the USB Type-C port is taken by the HDMI adapter, so you can't use it to charge the phone while working. Also, does it go searing hot?

During the aforementioned test conditions — Chrome, Facebook, YouTube, Play Store, and PUBG all open onscreen — we found that the battery drains at a pace of about 10% for every 20 minutes of usage. In other words, the Note 9 should be able to give you 3 hours of intense work under DeX mode. That's not too bad for on-the-go needs.

As far as heat goes — we were pleasantly surprised. The Note 9 was warm to the touch, but not hot in any area, about 30 minutes into using the setup.

But what if we cheat?

We placed the phone on a RavPower wireless charging pad to see if that can extend our usage time. And it did — it lowered the battery consumption rates down to about 3-4% per 20 minutes.

Of course, we wouldn't recommend using such a setup as your go-to DeX station. Putting the phone under intense workloads all the while charging it wirelessly will cause the battery to go hot for prolonged periods, significantly impacting its structural integrity and life.

Final words

All in all, we are pleasantly surprised and happy to report that DeX on the Note 9 works with an HDMI cable just as well as it would with a dedicated DeX dock. It's a great solution for on-the-go crunchers who need to connect to a large screen and a keyboard to finish up a quick task or two. Samsung also sells a multi-port adapter, which will let you connect a power cable, an ethernet cable, and a single USB accessory to the phone all at the same time.

However, we do feel that a DeX Pad is still the best choice, especially for those that would like to spend more time in DeX. The dock's fan will make sure that your device will work at cooler temperatures, which is definitely better for its longevity, it has two USB ports for a wired keyboard and mouse, and it will also provide power, making sure that you don't drain your battery while working in DeX.

The choice becomes even easier when you check out the price differences. A Samsung-branded HDMI adapter will set you back about $50, the multi-port HDMI adapter is $80, while the DeX Pad is now down to just $72. The latter is still light and easy to carry around, so it's worth it.

Related phones

Galaxy Note 9
  • Display 6.4" 1440 x 2960 pixels
  • Camera 12 MP / 8 MP front
  • Processor Qualcomm Snapdragon 845, Octa-core, 2800 MHz
  • Storage 128 GB + microSDXC
  • Battery 4000 mAh(29h 3G talk time)



1. Subie

Posts: 2426; Member since: Aug 01, 2015

Good review, and Good job Samsung!

2. rubyonrails3

Posts: 375; Member since: Oct 01, 2014

It should support 2K output at least. On my 4K TV text don't look sharp as I have to sit closer to TV.

14. ShadowUnleashed

Posts: 88; Member since: Feb 08, 2018

It does support 2K output.

3. monkeyb

Posts: 414; Member since: Jan 17, 2018

If we connect Samsung note 9 to a monitor that supports USB C. Will it charge the phone while using Dex? I personally will want to use the multi port usb-c spliter to charge and work at the same time.

4. strategic_developer

Posts: 1627; Member since: Jul 17, 2018

Can you not use the older DeX adapter with the Note 9? also did you try relaunching the DeX mode? because it is always slow the first time it loads, as any computer is the first time you load its software on a first boot. I found the DeX to be pretty useful. What I didn't like was the need to carry the DeX Station. Being able to just use a cable, will make it better and more portable. Now that the phone has more storage, I can now have a Windows 10 image loaded on my sdcard, that I can boot into when I need Windows on the go

10. Senthilg

Posts: 49; Member since: Apr 07, 2016

Can you boot to windows 10 from the sd card in DEX Mode? I am curious if I can get windows 10 working in Note 9 through SD card image I will get this phone immediately.

5. talon95

Posts: 1004; Member since: Jul 31, 2012

Have they allowed it to work in smart view mode? Why not just turn on DEX and send it wirelessly. I think it currently has too much lag (0.5 sec) but it will be nice when this becomes an option in a couple years.

15. Macready

Posts: 1830; Member since: Dec 08, 2014

It's not just lag, it's also a lot of data (realtime 1080P output), putting another big strain on battery consumption and heat production. It's surely possible, as right now I can cast 1080P to a TV and do multitasking on the phone at the same time too, but the video can be buffered (less constant strain on the Wifi chip) and that already taxes the battery significantly. Without having to be real time with minimal lag. Surely something we'll see in the future though. Maybe on the 7nm node...

6. Rigmaster

Posts: 234; Member since: Jan 22, 2018

Literally the most significant feature of the Note 9 and completely misunderstood due to poor marketing. Tablets have struggled to do this very thing in a satisfying way so Note 9 could/should be marketed as a tablet replacement. How about showing someone leaving a tablet device at home and truly being an on-the-go, power user. It's literally not marketed well at all. It's the one thing Apple devices can't/won't do.

17. cvcvcv

Posts: 1; Member since: Aug 22, 2018

Samsung dedicated a third of unpacked to DeX and it's prominently featured on the Note9 homepage. The tagline literally is "Turn your phone into a computer." what else would you propose they do?

7. jauling

Posts: 82; Member since: Feb 13, 2015

Check out Superbook by Sentio. Also, if a software only solution is your cup of team, check out the github repository called scrcpy.

8. japkoslav

Posts: 1552; Member since: Feb 19, 2017

What is the maximum supported resolution? 4K@60? 4K@30?

9. Crispin_Gatieza

Posts: 3166; Member since: Jan 23, 2014

No mention if DeX can be done via Miracast. No mention either if the phone can be used independently of the DeX session. If the answer to both of these is no, then Continuum remains the better system in spite of the lack of multiple windows.

11. rubyonrails3

Posts: 375; Member since: Oct 01, 2014

Battery is Okay not so great as I was expecting

12. ShadowWarrior

Posts: 170; Member since: Aug 08, 2017

Waiting for the day when I can truly use only my smartphone for everything and get rid of my laptop/desktop.

13. LikeMyself

Posts: 631; Member since: Sep 23, 2013

I get the same battery drainage using a type c to hdmi dongle on my s8+ without dex. Perfect for playing games. Dongle is better since no loose cable connections. It's $12 & ships very fast for free. Here's a link

16. japkoslav

Posts: 1552; Member since: Feb 19, 2017

You did not even test USB-C dock with power delivery ... brilliant.

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