Precision 5550 with High Refresh Rate Monitor

Hi, wondering if you can advise on my situation

I previously used a precision 5540 to output:

2560x1440 @ 144hz & 1920x1080 @ 60hz.

This was done directly via a thunderbolt 3 connection from the laptop to the WD19, which then had a display port connected to it that was attached to the 1080p monitor. The Dock has keyboard, mouse etc connected but no other cable for outputting video.

For the 1440p monitor I had to connect it directly via hdmi from monitor to laptop.

No other combination of connections worked. Using 2x displayport on the Dock or combination of hdmi and displayport on the Dock would not achieve the outcome I wanted (and also led to stuttering/shaking + screen retention issues in once case or in another combination, reduction in resolution).

I now have a precision 5550, which now has no hdmi port, instead 3x type c which according to you, 2 of which have thunderbolt 3. It came with a USB c to hdmi adapter but no matter what combination I have tried I cannot achieve:

2560x1440 @144hz & 1920x1080@ 60hz as I did with the precision 5540.

The best I can achieve is the above at 60hz. What can I do to get the 1440p monitor running at 144hz?

If it matters I am running Ubuntu on the 5550 while windows on the 5540. Using xrandr on ubuntu I can see no possible option of 144hz @ 2560x1440 even when connecting the 1440p monitor by itself.

I will be testing a USB c to hdmi cable today direct from laptop to monitor but doubtful it will work at this point.

@Soulaez  If memory serves, the USB-C to HDMI adapter that comes with the Precision 5550 also has a USB 3.0 port on it -- is that correct?  If so, that adapter would be configuring the USB-C link to support both video and USB 3.0 data, even if nothing is plugged into the port at that time.  And in that case, supporting USB 3.0 data on a USB-C link requires cutting video bandwidth in half.  And since the Precision 5550 only supports DisplayPort 1.2/HBR2 over USB-C, a half-bandwidth link is only enough for 1440p 60 Hz.  A USB-C to HDMI 2.0 cable, or an adapter that ONLY provides an HDMI 2.0 output, should allow 144 Hz -- although if that display has a DisplayPort input, I would recommend a USB-C to DP cable instead, for a reason I just wrote up most recently in this thread but that comes up surprisingly often.

Using a regular USB-C dock like the WD19 would have the same limitation, since it of course is also setting up the USB-C link for USB 3.x.  However, if you were to get an actual Thunderbolt 3 dock, like the WD19TB, you would be able to run both displays through the dock because with that system, a TB3 dock will be able to tap into 4x more video bandwidth than a regular USB-C dock -- while also running USB 3.x data.  But based on your displays and how the WD19TB allocates its video bandwidth with HBR2 systems, you'd likely need to put one of your displays on the "downstream TB3" port at the edge of the dock -- not to be confused with the USB-C port near the HDMI output.  (The regular WD19 doesn't have this downstream TB3 port.)

@Soulaez Sorry to hear that even the cable isn't solving this for you.  I buy a lot of different Anker products and have consistently had good luck with them.  I'd definitely update your drivers and BIOS if updates for those are available.  Otherwise, I'm curious whether the display lights up if you just set it to 60 Hz as a test.  I'd also be curious whether it displays to the external display at the BIOS Setup interface to eliminate drivers entirely, although I doubt that would be 144 Hz.  To do that, you'd have to start the system while the lid was closed by using the Power button on the dock.  If you can't get it to work at all, then this may be another one of those interoperability cases I described in that thread I linked above, in which case the next vendor I'd recommend would be Cable Matters, since I buy a fair amount of their cables/adapters and have had good luck with them too.

Alternatively, if your gaming PC has a native HDMI 2.0 output, could you use your gaming PC on HDMI to free up the DP input for your Precision?  Or does the DP input offer additional functionality like G-Sync or a higher refresh rate that isn't possible on HDMI?

@jphughan I would love to use USB-C to DP cable but unfortunately I cannot. The 1440p monitor I use is the Dell S2721DGF, which comes with only 1 DP port, that port I used for my gaming PC to run at 165hz so I am left with no choice but to use UCB-C to HDMI for the 5550, unless I swap the ports every single day which defeats the point of the WD19 dock. 

Correct the USB-C to HDMI adapter included with the Precision 5550 also has a USB 3.0 A port.

That's great that usb-c to hdmi should work, so I just received this https://us.anker.com/collections/cables/products/anker-nylon-usb-c-to-hdmi-4k-cable and spoken to anker, they confirmed it supports 2560x1440p @ 144hz. Weird thing is after plugging it in, on my ubuntu 5550, although the display registers and 2560x1440p @ 144hz is an option (FINALLY - it refused to show up before using any previous cables) the monitor remains blank.....saying no input detected....any thoughts on what I can do? Will see if updating drivers does anything as at the moment no matter what I do the monitor doesn't show anything with ankers cable.

Also I would love to have the WD19TB but unfortunately my workplace doesn't provide that, so I'm stuck with the WD19 unless I choose to spend 200+£ to get it, so not happening really.

@jphughan I have had great experiences with Anker too, I even bought their 7 in 1 usb c hub yesterday for my Chromecast and it works great!

Hopefully this is just a software issue and drivers + BIOS update helps. I think I tried 60hz @ all resolutions for the 1440p monitor I have but don't think it worked. I don't recall for certain so will try again and let you know. Same with trying to output when the laptop lid is down, that's usually the first method I used with my dock and laptops.

Will try cable matters too if those don't work.

Correct so I could use HDMI to HDMI for my gaming pc and monitor BUT this would cap my refresh rate to 144hz as that is the max it supports on HDMI unfortunately, so that's really a last resort option if I can avoid it. And yes I'm not 100% certain but I believe G-Sync over HDMI is a no go.

@Soulaez  Traditional G-Sync is only possible over DisplayPort.  NVIDIA introduced a new variant of G-Sync that's only available on 16 Series and above GPUs and is designed to be used with some LG OLED TVs, but I'm pretty sure that's just a rebrand of HDMI VRR, not something proprietary to NVIDIA.  I'm not certain about that though.  Anyway, just purely out of curiosity since I've never used high refresh rate displays, can you tell the difference between 144 and 165 Hz?

@Soulaez  Totally agree that hanging onto G-Sync is worthwhile over a fixed high refresh rate, in fact I would bet that G-Sync 144 Hz would be better overall than 165 Hz fixed.  When you have a fixed refresh rate, you can either have V-Sync on or off (or Adaptive V-Sync, but that just switches between using it or not on the fly).  When V-Sync is off, you can get frame tearing.  When V-Sync is on, you avoid that, but that only works well if the GPU can sustain a frame rate to match the refresh rate -- so if you're running 165 Hz without G-Sync, never falling below 165 fps is a pretty tall order even for a modern GPU.  If the GPU ever falls behind when V-Sync is on, the GPU starts repeating frames, which appears as judder-y motion and/or lag.  That was the whole point of G-Sync, to give you a way to avoid frame tearing without the risk of judder or lag by having the display adjust its refresh rate based on the frame rate the GPU can sustain at any given time.

@jphughan Yeah so I have a 3060ti so the GPU supports VRR but the monitor doesn't have HDMI 2.1 so can't use that at the moment. Regarding 165 vs 144hz, yeah I can tell the difference, though I have only tested it in the windows desktop, moving the mouse around it definitely feels smoother at 165hz. Having said that...I haven't tested it on games, and admit that if was gaming at 144 vs 165 I probably wouldn't notice a difference except when switching between the two and running tests. Sitting down to an untested computer that's running 165 or 144hz? Don't know as haven't tried it, probably would struggle to tell the difference. Would still prefer to have main desktop on DisplayPort for G-sync anyway.

So, weirdly enough I got it to work. Plugging out the other HDMI cable that was attached to my monitor resulted in the video output showing up. (The other end of  the cable was not connected to anything).

Not sure why this happens but I now have 1440 @ 144hz on my 5550 + my other monitor @ 1080p @ 60hz,  so same as my original set up.

• Laptop
  Dell Precision 5550
  i7-10850H @ 2.70GHz
  64 GB RAM
  NVIDIA Quadro T1000
  4K built-in display
  Windows 11 23H2
• Monitor
  LG 38WR85QC-W
• Dock station
  Dell WD19TBS

Unfortunately, no matter what combinations of connection the monitor to my laptop I try, I can't get over 4K@75Hz (more precisely 74,98Hz) with this setup. This is what I've tried so far:

1. USB-C -> USB-C dock (the Thunderbolt 3 port at the edge of the dock)
   Result = 4K@75Hz with HDR option available
2. USB-C -> USB-C laptop (one of the 2 Thunderbolt 3 ports)
   Result = 4K@75Hz with HDR option available
3. DP -> DP dock
   Result = 4K@75Hz with HDR option available
4. DP -> USB-C laptop (with a reduction cable)
   Result = 4K@75Hz with HDR option available
5. DP -> USB-C dock (with a reduction cable, to the Thunderbolt 3 port)
   Result = 4K@75Hz with HDR option available
6. HDMI -> HDMI dock
   Result = 4K@30Hz with HRD option unavailable
7. HDMI -> HDMI laptop (using the included Dell USB-C adapter)
   Result = 4K@30Hz with HRD option unavailable