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1576
November 1st, 2021 08:00
Precision 7530 and WD19TB only driving external monitors in 29Hz
I have a Precision 7530 hooked up via the thunderbolt port to a WD19TB. The laptop recognizes the docking station as expected in the Thunderbolt Software. I'm trying to drive three Dell U2718Q monitors at QHD (2560 x 1440) resolution. Ideally, I want the output to be running at 60hz for each monitor, however, it is driving them all at 30Hz. According to the documentation (if I'm reading it correctly), this configuration should be possible with this laptop and dock while using the thunderbolt port. While trouble shooting, I noticed that even if I use a single monitor (hooked up to the DisplayPort on the dock) configured to 1080p, it still drives it at 30Hz. Things I've tried so far:
- Updated all drivers (specifically the Intel UHD Graphics driver)
- Updated the firmware on the WD19TB
- Changing to/from various resolutions
- Changing the number of monitors plugged in to the dock
- Tried using only the HDMI port
- Tried using only a single DP port
- Tried using the other thunderbolt port
- Tried to explicitly set the refresh rate for the monitors via Display Settings->Advanced display settings->Display adapter properties for Display N->Monitor->Screen Refresh Rate (this resulted in nothing being displayed on the monitor that had this setting changed, despite what refresh rate I tried to select other than the one it's defaulting to)
Another thing to note, this laptop has an NVIDIA Quadro P2000 display adapter in it as well, and I am able to connect these monitors to the mini DP port that is for that display adapter on the back of the laptop and have it display in full 4K at 60Hz no problem (so I know it's not an issue with the monitors themselves).
My questions are:
- Is this configuration I'm trying to achieve possible with this laptop/dock/monitors?
- If so, what exactly am I missing/doing wrong?
Thanks in advance!
bdschaue
3 Posts
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November 1st, 2021 14:00
@jphughan
To answer your questions:
1) I want to run in the lower resolution because there are some weird legacy programs that I have to use that windows doesn't seem to be able to scale accordingly (and thus are super tiny), although, for the sake of debugging this, I have switched over to 4K.
2) I have a power adapter directly connected to the 7530 itself in addition to the dock for this very reason.
That being said, I kind of have things working: all three displays running at 4K@60hz using the NVIDIA GPU. There is one rub, however: I can only seem to use two of the three display outputs on the dock at any given time. Either both DPs can be hooked up, or one of the DPs and the HDMI port. The third output always gets shut off whenever I have all three of them plugged in. However, running the two DPs off the dock and then the third monitor connected to the laptop's mini DP port directly seems to get the resolution/refresh rate that I want on all three monitors, and it's running fine. Does that make sense that I wouldn't be able to drive all three off the dock? Is that related to the power issue you were referring to, possibly? I'm satisfied with how it's working now, but ideally I'd like to drive them all off the dock, if possible.
How I got this "working": manually installed the latest NVIDIA Quadro drivers (for whatever reason, NVIDIA Control Panel wasn't installed on this machine), then, went into the BIOS and enabled the "discrete graphics" output mode (which essentially allowed for the NVIDIA GPU to take over). I think the latter, like you suggested doing in your reply, is what really did the trick.
Thank you for your help thus far!
bdschaue
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November 1st, 2021 12:00
Pinging @jphughan as he seems to be the guru for this stuff!
jphughan
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14K Posts
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November 1st, 2021 13:00
@bdschaue I had actually opened this thread a few hours earlier when you had only written your initial post but hadn't gotten around to reading it and replying yet. But thanks for thinking of me and the kind words!
Triple QHD 60 Hz should be possible, although I can't say I'd recommend running a 4K display at QHD resolution. But I'll ignore that for now. My guess as to the issue here is that Windows is only changing the desktop (render) resolution to QHD, while leaving the active signal resolution set to the 4K native resolution of the display. There are some good reasons for doing this, but the drawback that's relevant to your situation is that if you only drop the desktop resolution while keeping a higher active signal resolution, you don't free up any bandwidth. You don't have enough bandwidth for triple 4K 60 Hz, so you'd have to force down the active signal resolution.
One key question here for your particular system is whether you have "Graphics special mode" enabled in your BIOS. At least that's what it used to be called; Dell may have changed that name with a BIOS update to something more descriptive. But if that's disabled, then the Intel GPU would control the display outputs, with the NVIDIA GPU operating as a render-only device through NVIDIA Optimus. In that case, I believe that changing the resolution in Intel Graphics Control Panel / Command Center rather than Windows Display Settings should change the active signal resolution rather than just the desktop resolution. If "Graphics special mode" is enabled, then the NVIDIA GPU has direct control of the display outputs, in which case try changing resolutions using NVIDIA Control Panel to see if that accomplishes the same thing.
And lastly, a WD19TB isn't an ideal companion for a Precision 7530 since the WD19TB can only provide up to 130W of power. The dock actually meant for Precision 7000 Series systems is the WD19DC (or DCS), which can supply up to 210W of power because it plugs into both of the USB-C/Thunderbolt ports on the system. But if you also use that dock with another system that isn't a Precision 7000 Series model, then the DC/DCS can be an issue because it is NOT a Thunderbolt dock. It's a "dual USB-C" dock, but when used with other systems it would operate only in single connector mode at a functional level equivalent to the regular WD19, not the WD19TB. So if you need to run triple QHD from another system, then the WD19TB is probably the better overall choice. You'll just need to keep the 7530's own power adapter directly connected in order to maintain optimal performance.
Hopefully this helps!
jphughan
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14K Posts
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November 1st, 2021 14:00
@bdschaue Happy to help however I can! Yes, it is absolutely expected that you would not be able to run triple 4K 60 Hz through the dock. The bandwidth required for that would be about 37.5 Gbps of effective bandwidth (before any overhead). Thunderbolt 3 supports 40 Gbps, although I'm not sure if that's with or without overhead. But even if it's without overhead, that would mean that even USB 3.x Gen 1 (5 Gbps) would be bottlenecked by your displays. And that even assumes that all of Thunderbolt's bandwidth could be allocated to video bandwidth, which isn't the case. Depending on whether the system supports DisplayPort HBR2 or HBR3, Thunderbolt will carry either eight lanes of HBR2 or five lanes of HBR3. Both of those setups are enough for dual 4K 60 Hz, but not even close to what's needed for triple 4K 60 Hz.
In any case, if you've got a setup you're happy with, then that's what matters most. I'm surprised you weren't able to achieve the desired setup with the Intel GPU controlling the outputs, and be aware that giving the NVIDIA GPU direct control of the outputs may result in reduced battery life if you ever run external displays while on battery power. But with a 7530 you might not be overly concerned about battery life anyway. Feel free to ping me if I can ever offer any further help!