m17, with dual Thunderbolt monitors

Question

Hello,I have a new Alienware m17 laptop with Nvidia RTX 2070 Super and the Thunderbolt 3 port. I also have two Samsung Thunderbolt 3 monitors that are supposed to be capable of daisy chaining. When I connect the monitors as per the manual, only one monitor displays at a time. Sometimes if I unplug and plug back in, the other monitor displays, so it's randomly picking which one to display.  The Thunderbolt control center shows both displays as being connected. The weird thing is, I had this problem when first trying to connect, and then for reasons unknown to me, it worked all of a sudden, and continued to do so for a couple of days. Then today after moving my laptop away from the monitors for a few hours, it was once again unable to connect to both displays at the same time. Any idea how I can get this working reliably (without resorting to an additional connection via HDMI)? Samsung was less than useful. Thanks in advance.

jphughan · Accepted Answer

@Kram73 Dual 4K 60 Hz does consume a lot of TB3 bandwidth even before considering any other data running on the link (such as USB 3.x), but Thunderbolt products have to be tested and certified by Intel. It's not just a standard without any enforcement like regular USB cables, so having products that don't perform up to spec should be much more rare in the Thunderbolt world. There are a handful of cables that are technically TB3 cables since they use a USB-C connector but are only rated for TB2 20 Gbps speeds, typically because they're too long to support TB3 40 Gbps, but if you have a typical TB3 40 Gbps cable, then it should support dual 4K 60 Hz if it's performing the way it's supposed to be. And yes your laptop would support TB3 and dual 4K 60 Hz. Many older and lower-end systems that have TB3 can do that.

Based on the behavior you're describing and especially the fact that things apparently worked as expected for a short time, a firmware issue sounds like a distinct possibility. Make sure the displays have the latest firmware if updates are available for them, and then on your system run Alienware Update to make sure you have the latest BIOS, TB3 controller firmware, TB3 drivers, and GPU drivers.

Kram73 · Answer

I'm now wondering if it is possible the TB3 cables that came with my monitors are not sufficient to transmit enough data for dual 4K, and were only intended for single connection?

It's a bit expensive to test if this is the case, so I'd prefer to know if my laptop actually supports it. Although, given it worked this morning, it does make me wonder if it's just on the edge of being able to transmit enough data.

Kram73 · Answer

Thank you so much for the reply.
I have updated all the software, so I think the last thing to try is the cables. I suspect the 40 vs 20 bandwidth could be a possibility.
Thanks for taking the time to reply.

Alienware

m17, with dual Thunderbolt monitors

Was this post helpful?