Multiple monitor set up

@ColinW_611  Ok, a few things to address here.

First, yes the TB16 certainly had more than its fair share of complaints until it was replaced by the WD19 dock family models. It also can’t power your 7730 adequately since it can only supply either 90W or 130W, depending on whether your TB16 was ordered with the 180W or 240W power supply, respectively. So if you’re relying on it as a power source rather than keeping the system’s power adapter attached, you’ll be experiencing reduced performance especially when the discrete GPU is active. And if you’re avoiding that problem by keeping the system’s own power adapter attached as well, then you’re of course tying up your system’s power adapter rather than having it freed up for use elsewhere per the regular dock experience. Dell released the TB18DC specifically to provide up to 210W of power to Precision 7000 Series systems from the 7x30 onward, which it achieved by plugging into TWO of the USB-C/TB3 ports, but that model has since been replaced by a WD19 model (more on that in a moment).

All that said, it’s not accurate that the TB16 only has mDP and HDMI. It also has a full-size DP output, as well as a downstream TB3/USB-C output that can be used for video output. And as noted in the TB16 User Guide here, specifically the Display Resolution Table, if you want to run dual 4K 60 Hz, you need to use some combination of the mDP, full-size DP, and downstream TB3/USB-C ports to get there. So if you don’t want to spend more money on a new dock, you should at least be able to solve that problem with your current hardware. I’d recommend the DP and mDP outputs unless you happen to have a USB-C to DisplayPort cable lying around and don’t need that downstream TB3 port for something else, like a Thunderbolt peripheral of some kind.

But if you still want a new dock even after getting dual 4K 60 Hz out of your TB16, then the dock you want is the WD19DCS. It is the replacement of the TB18DC that I mentioned above, and as such is specifically designed for Precision 7000 Series systems from the 7x30 models onward because it is the only one capable of delivering up to 210W of power to meet their power requirements. The other WD19 dock family models top out at either 90W or 130W. And the WD19DCS would be able to run dual 4K 60 Hz too, of course. However, be aware that it is not a Thunderbolt dock like the TB18DC; it’s actually a “dual USB-C” dock. The only practical impact this would have on you would be if you did in fact have an actual Thunderbolt peripheral plugged into your TB16. You would not be able to use that through the WD19DCS, or best case it would operate at reduced functionality in USB-C backward compatibility mode if it supported that at all. But if you don’t have any TB3 peripherals, then you shouldn’t see any issues upgrading to the DCS.

@ColinW_611  One additional tidbit that I forgot to mention. I don’t think the HDMI output on the TB16 supports 4K 60 Hz, but even if it did, the HDMI input on your P2415Q definitely wouldn’t. In the latter case, which may also apply to the former, the reason is that the product predates the HDMI 2.0 specification, which is when HDMI gained support for 4K 60 Hz. But given that you have two identical displays that each have both mDP and full-size DP inputs, and you have a TB16 with mDP and full-size DP outputs, I’m not sure why you chose to use the mDP and HDMI outputs rather than mDP and full-size DP. The P2415Q came with a full-size DP to mDP cable, so you could have used that type of cable on both displays. Connect the TB16’s mDP output to the full-size DP input of one display, and the TB16’s full-size DP output to the mDP input of the other.