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It’s because the Dxxxx series docks use DisplayLink rather than tapping into native GPU outputs. DisplayLink uses a driver to have the CPU and GPU compress video for transmission as regular USB traffic, and then a chip in the dock decompresses it and transmits it to the displays. That’s why you’re seeing all that CPU activity and horrible performance. DisplayLink is fine for basic productivity tasks, but when lots of the display area is changing at once, such as when gaming or watching full screen video, that’s a lot more work to do, so your CPU gets busy and you can end up with jerky/judder-y video. You can also see these types of issues if your USB bus is busy with other traffic, such as a large file transfer. And even without any of that, DisplayLink’s compression isn’t lossless, so you can end up with visible judder or blocky video for that reason alone. And on top of all that, you didn’t specify what system you’re using, but if it has both an Intel GPU and discrete GPU, then due to a limitation within Windows, only the Intel GPU can be used with displays connected via DisplayLink. The discrete GPU wouldn’t get used at all unless it’s the only one in the system.
You need a dock that taps into native GPU outputs. If your system has Thunderbolt 3, then you’d want the WD19TB dock if you have dual 4K displays. If your system only has USB-C, then the WD19 uses native GPU output, but it can’t handle dual 4K 60 Hz. And if you get the WD19, make sure you get the version with the correct power supply size based on your system’s requirements. The WD19TB only comes with the larger power supply option.
The D6000 can handle more displays at higher resolution than those other docks precisely because of its compression behavior, and also because again it doesn’t use native GPU outputs, but as I’ve just described, that brings significant drawbacks. It’s really meant as a business dock for use cases involving email and spreadsheets. Its main value proposition is that it can be used with both USB-C and USB-A systems, which means companies that currently have a mixture of older systems with traditional docking connectors and newer systems with USB-C/TB3 can standardize on this one dock model. That’s especially useful for companies with “hotel desk” setups. But it’s absolutely not the right choice for gaming.
It’s because the Dxxxx series docks use DisplayLink rather than tapping into native GPU outputs. DisplayLink uses a driver to have the CPU and GPU compress video for transmission as regular USB traffic, and then a chip in the dock decompresses it and transmits it to the displays. That’s why you’re seeing all that CPU activity and horrible performance. DisplayLink is fine for basic productivity tasks, but when lots of the display area is changing at once, such as when gaming or watching full screen video, that’s a lot more work to do, so your CPU gets busy and you can end up with jerky/judder-y video. You can also see these types of issues if your USB bus is busy with other traffic, such as a large file transfer. And even without any of that, DisplayLink’s compression isn’t lossless, so you can end up with visible judder or blocky video for that reason alone. And on top of all that, you didn’t specify what system you’re using, but if it has both an Intel GPU and discrete GPU, then due to a limitation within Windows, only the Intel GPU can be used with displays connected via DisplayLink. The discrete GPU wouldn’t get used at all unless it’s the only one in the system.
You need a dock that taps into native GPU outputs. If your system has Thunderbolt 3, then you’d want the WD19TB dock if you have dual 4K displays. If your system only has USB-C, then the WD19 uses native GPU output, but it can’t handle dual 4K 60 Hz. And if you get the WD19, make sure you get the version with the correct power supply size based on your system’s requirements. The WD19TB only comes with the larger power supply option.
The D6000 can handle more displays at higher resolution than those other docks precisely because of its compression behavior, and also because again it doesn’t use native GPU outputs, but as I’ve just described, that brings significant drawbacks. It’s really meant as a business dock for use cases involving email and spreadsheets. Its main value proposition is that it can be used with both USB-C and USB-A systems, which means companies that currently have a mixture of older systems with traditional docking connectors and newer systems with USB-C/TB3 can standardize on this one dock model. That’s especially useful for companies with “hotel desk” setups. But it’s absolutely not the right choice for gaming.
In addition to the post above, one other thing you may want to consider is getting rid of the 4K 27” displays in favor of 1440p 27” displays, for a few reasons:
- 4K at 27” gives you a pixel density that’s high enough that you’ll have to enable scaling for things to be legible (and Windows and various applications still don’t handle scaling consistently well) but not high enough to give you a truly sharp Apple Retina-style experience (you need 5K resolution at 27” for that). So in that regard, unless you specifically need 4K resolution for something like editing 4K video, 4K 27” is sort of the worst of both worlds. That’s why when I just bought a pair of 27” displays, I specifically avoided the U2718Q and instead bought the U2717D, which is 1440p.
- Lower resolution means your system will have an easier time rendering games at the native resolution of the displays, and you won’t even be able to tell the difference in pixel density.
- If you don’t have Thunderbolt 3 but do have USB-C, you can run dual 1440p displays if you connect the displays directly to the USB-C port with a USB-C to DisplayPort cable rather than running through a dock, for technical reasons I can explain if you’re curious. You can even do it through a single cable connection if your displays support DisplayPort daisy chaining. By comparison, running dual 4K displays using native GPU connectivity requires Thunderbolt 3, unless you have two separate display outputs on that system that are each capable of 4K 60 Hz and you’re ok using two cables for your displays.
@loyukfai-new I'm not sure what happens in that scenario. The documentation indicates that when you have 3 displays attached, the HDMI display uses DisplayPort Alt Mode wile the other 2 displays use DisplayLink, but I don't know if the HDMI output can work on its own via DisplayPort Alt Mode if it's the only display connected and there are no DisplayLink drivers installed. Additionally, I think Windows Update will provide at least basic DisplayLink drivers automatically now -- but I'm not 100% sure about that.
But DisplayLink is not really another GPU. DisplayLink displays are not actually connected to any GPU at all. The issue with dual GPU systems it that DisplayLink displays can only have their content accelerated by the system's primary GPU. So if you have an Intel+NVIDIA setup, you won't get the benefit of the NVIDIA GPU's rendering performance on your DisplayLink displays.
@d6000-user That should be a straightforward setup. However, DisplayPort to VGA adapters include active signal converter chips since DisplayPort does not natively support VGA output, and those signal converter chips seem to cause problems sometimes. I've seen this happen with USB-C to HDMI adapters where the same design exists since USB-C uses DisplayPort for video. Sometimes one brand off USB-C to HDMI adapter will work with one laptop but not another, while some other brand of USB-C to HDMI adapter will work with both laptops, even though both adapters should have worked with both laptops. If you have a way to test whether the DisplayPort output works for regular DisplayPort, that might be a useful data point just to rule out an issue with the port on the D6000 itself, but the D6000 has two DP outputs, so if you're seeing this behavior on both ports, it's unlikely that both of them would be bad while HDMI works as expected. So you might just need a different brand of DP to VGA adapter. I've had good luck with StarTech and Cable Matters for these types of products, just to name a couple of solid vendors.
@d6000-user Just one additional thought: Does the display you're trying to use have ANY other input besides VGA? Even if you don't have DisplayPort or HDMI inputs on that display, do you maybe have DVI? If so, you could get a DisplayPort to DVI adapter plus a DVI cable instead, or maybe even a DisplayPort to DVI cable if you can find one. The D6000's DisplayPort outputs do have native support for HDMI/DVI signaling because they support "Dual Mode DisplayPort", so that would allow you to use a simpler type of adapter, and you'll get a higher quality image since ancient VGA is an analog signal, whereas DVI, HDMI, and DisplayPort are all digital signals. I'd try to avoid VGA if at all possible.
