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January 16th, 2021 14:00
Dell XPS 17 9700 External Monitor question
I want to use an external monitor with my dell XPS 17.
This is the model I have: https://www.dell.com/en-ca/shop/dell-laptops/xps-17-laptop/spd/xps-17-9700-laptop/nxps179700_s2000e
I don't know much about external monitors, I will be using the external monitor only with the laptop lid closed so these are my questions:
1. Will a 1440p at 60hz resolution monitor affect laptop performance (battery usage, speed, etc) compare to a 1080p at 75hz monitor?
2. It says the battery in the laptop is 97Wh but this USB-C monitor (https://www.dell.com/en-ca/shop/dell-27-usb-c-monitor-p2720dc/apd/210-auln/monitors-monitor-accessories#techspecs_section) I am interested in only has 65W power output
a) will be able to power the laptop? OR will I have to also plug it into the charger while I am using it?
3. If I use a USB-c monitor but also plug it into the charger will it damage the battery?
4. if the resolution on my laptop screen is 1920 x 1200 but the external monitor I use is 2550x1440 at 60hz will it affect laptop performance or cause heating issues?
5. Does using the laptop with the screen off affect the cooling? Is it okay to put in closed vertically in stand while plugged into an external monitor?
Can anyone help me out with these questions?
Thank you!
ejn63
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January 16th, 2021 15:00
1. It will consume more system resources -- but the system should easily handle that monitor.
2. Be careful not to confuse energy (97 WHr) with power (65 W). These system ship with a 130W AC adapter; it's unlikely they'll run at full speed without the original AC adapter connected.
3. See above. You will need a separate power supply for the monitor and system.
4. See #1.
5. Just from a radiant standpoint, you're better off with the system horizontal rather than vertical for heat dissipation purposes.
TerryGa
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March 21st, 2021 11:00
65W power output from the monitor charges my XPS 17 and I could use the charger but there is no need.
jphughan
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March 21st, 2021 12:00
@TerryGa As mentioned by ejn63, a battery's WHr rating relates to energy storage capacity. The display's 65W USB PD rating refers to energy delivery rate. While it's true that the XPS 17 9700 can charge from a 65W power source, it is designed for a 130W power source. So if you try to use it from a 65W power source, you will likely see much slower charging and also significantly throttled CPU and especially GPU performance. Dell shipped the system with a power adapter capable of supplying twice as much power as the USB-C display you're planning to use as a power source. You should not expect that you can cut your system's power source capacity in half without seeing some negative side effects.
jphughan
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March 21st, 2021 13:00
@TerryGa One other point I forgot to mention in my reply above is that the XPS 17 9700 uses something Dell calls "Hybrid Power" or "Battery Power Boost". Basically, even the 130W available from the system's power adapter isn't always enough power to run the system properly, so under heavy loads the XPS 17 9700 will actually drain the battery as an auxiliary power source even while connected to a 130W charger. So if you run a heavy load long enough, you can drain your battery pretty far, and at that point the system will start throttling its performance in order to avoid going dead even while you're connected to power. This behavior of draining the battery even while connected to power can of course be quite annoying, because it means that if you could potentially have the system connected to a charger for several hours and still have a low battery when you eventually disconnect. It also imposes wear and tear on the battery itself -- all because Dell decided to ship this system with an undersized power source. But the point is that since this happens even when using the system's normal 130W power adapter, if you try to run your system from a 65W power source, the battery drain and performance throttling will be even more severe. If you only use your system for light workloads, then maybe you don't care. But if you ever think that your battery is charging very slowly or performing slower than you would have expected, then it will probably be cause you're trying to run your system from a severely undersized power source.