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605
November 22nd, 2020 10:00
Dual screen setup (Vostro 5481 + WD15 docking station)
Hello,
I've been using Vostro 5481 together with a WD15 docking station and a P2418D 2560x1440 60Hz monitor for some time. Now I'd like to add a second monitor to this setup. However, the WD15 manual states that the station supports either a single 4K 30Hz monitor or two Full HD 60 Hz monitors. So, it seems that my situation is somewhere inbetween.
My question is what's the highest resolution of a monitor I can add to my current setup without losing resolution or frequency of my primary P2418D monitor. I realize that I have to aim for something low-res. Would a WXGA (1366x768) monitor such as E1920H do the job?
Thanks!
jphughan
9 Legend
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14K Posts
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November 23rd, 2020 09:00
@benny19 The 10.8 Gbps figure is "raw" bandwidth, which includes signal/protocol overhead. The 8.6 Gbps figure I quoted is "effective" bandwidth. You can use either type of figure, but you have to be consistent when comparing the bandwidth from the system to the bandwidth required by the display. I used effective bandwidth figures in both cases in my post. The WD19's manual is a bit more detailed about this.
jphughan
9 Legend
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14K Posts
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November 22nd, 2020 11:00
@benny19 With the WD15, you have 8.6 Gbps of usable video bandwidth coming from the system. A QHD/1440p 60 Hz display consumes about 5.6 Gbps. A 1080p display consumes about 3.2 Gbps. 1366x768 should work. If you're considering potential setups, I’d recommend calculating the percentage of total pixels of your potential setup compared to 1920x1080 or 2560x1440 and taking the corresponding percentage of display bandwidth required by those setups to figure out what it would require. Alternatively, you could get a USB dongle that used “indirect display” technology such as DisplayLink (not to be confused with DisplayPort) and plug that into a USB port on your dock. DisplayLink sends video as USB data, so it doesn’t count toward your bandwidth limit. Depending on the adapter, you could add a 4K 60 Hz display that way. But DisplayLink does have some drawbacks that can be significant in some use cases, which I’ve written about in the post marked as the answer in this thread. However, if your use case is unlikely to be affected, you might prefer that.
The alternative would be to plug the additional display directly into the system’s HDMI output, in which case its bandwidth wouldn’t have to be covered by the dock connection. Not as convenient, but you’d be able to run a higher resolution without the drawbacks of DisplayLink.
benny19
2 Posts
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November 23rd, 2020 06:00
Thanks for the response! I've been looking into it a bit more and the WD15 manual says on page 30 that it supports up to 10.8G video bandwidth. Am I missing something here?