Question for Linus regarding your personal rig.

[KuJoe]

Hey @LinusTech, I really like the idea of using the single Thunderbolt cable for all of your IO but are you noticing an impact in performance for gaming at all? If so how much? I'm doing something similar over USB 3.0 and noticing a 25-50% performance hit when I have my monitors plugged into my hub/dock versus directly into the video cards. I was wondering if you could run some benchmarks on your rig and see if there is a performance impact or not before I drop any money on switching to Thunderbolt over USB 3.0. Thanks!

 

Anybody else who wants to chime in it would be appreciated.

[TheLaserCucumber]

USB 3 has a throughput of 5Gbit/s, while Thunderbolt 3 has a Throughput of 40Gbit/s. I think this performance impact would be gone with Thunderbolt.

[KuJoe]

6 hours ago, TheLaserCucumber said:

USB 3 has a throughput of 5Gbit/s, while Thunderbolt 3 has a Throughput of 40Gbit/s. I think this performance impact would be gone with Thunderbolt.

Are HDMI cables really using 5Gbit/s of bandwidth for games? That's insane.

[Sniperfox47]

On 20/12/2016 at 11:04 PM, KuJoe said:

~snip~

18 hours ago, KuJoe said:

Are HDMI cables really using 5Gbit/s of bandwidth for games? That's insane.

Problem with HDMI over USB 2.0/3.0/3.1 is that your video card is rendering and then doing a memory copy of the whole framebuffer to system memory, and then that's getting processed further by a DisplayLink encoder driver which transmits the data via USB to the dock, which then decodes it before displaying it.

 

It's not so much the cable bandwidth that's the problem as the extra latency and frame copies, since the GPU can't start working on a new frame until the whole framebuffer is copied out. Latency shoots through the roof too because of all of the extra steps.

 

Thunderbolt on the other hand can encapsulate a native DisplayPort signal straight from your GPU. That means more bandwidth needed for transmission, as much as the DisplayPort would normally use rather than being compressed like DisplayLink is, but results in much better results on the far end of the bandwidth is there.

 

To get the best results you either need a Thunderbolt monitor [edit] motherboard with a passthrough port, a Thunderbolt AiC with a DisplayPort passthrough, or a Thunderbolt + DisplayPort merger of some kind.

[mark_cameron]

1 hour ago, Sniperfox47 said:

Problem with HDMI over USB 2.0/3.0/3.1 is that your video card is rendering and then doing a memory copy of the whole framebuffer to system memory, and then that's getting processed further by a DisplayLink encoder driver which transmits the data via USB to the dock, which then decodes it before displaying it.

 

It's not so much the cable bandwidth that's the problem as the extra latency and frame copies, since the GPU can't start working on a new frame until the whole framebuffer is copied out. Latency shoots through the roof too because of all of the extra steps.

 

Thunderbolt on the other hand can encapsulate a native DisplayPort signal straight from your GPU. That means more bandwidth needed for transmission, as much as the DisplayPort would normally use rather than being compressed like DisplayLink is, but results in much better results on the far end of the bandwidth is there.

 

To get the best results you either need a Thunderbolt monitor with a passthrough port, a Thunderbolt AiC with a DisplayPort passthrough, or a Thunderbolt + DisplayPort merger of some kind.

Displaylink is useful for productivity / office applications however, for high demand graphics and/or gaming I fully agree. Having used displaylink - its fairly good but native display from GPUs via dvi, displayport or HDMI or thunderbolt is always going to be fair superior.

[Sniperfox47]

7 minutes ago, mark_cameron said:

Displaylink is useful for productivity / office applications

Exactly.

[KuJoe]

15 hours ago, Sniperfox47 said:

Problem with HDMI over USB 2.0/3.0/3.1 is that your video card is rendering and then doing a memory copy of the whole framebuffer to system memory, and then that's getting processed further by a DisplayLink encoder driver which transmits the data via USB to the dock, which then decodes it before displaying it.

 

It's not so much the cable bandwidth that's the problem as the extra latency and frame copies, since the GPU can't start working on a new frame until the whole framebuffer is copied out. Latency shoots through the roof too because of all of the extra steps.

 

Thunderbolt on the other hand can encapsulate a native DisplayPort signal straight from your GPU. That means more bandwidth needed for transmission, as much as the DisplayPort would normally use rather than being compressed like DisplayLink is, but results in much better results on the far end of the bandwidth is there.

 

To get the best results you either need a Thunderbolt monitor with a passthrough port, a Thunderbolt AiC with a DisplayPort passthrough, or a Thunderbolt + DisplayPort merger of some kind.

Thank you for explaining this, this is the exact technical information I needed and was looking for.

[Sniperfox47]

2 hours ago, KuJoe said:

Thank you for explaining this, this is the exact technical information I needed and was looking for.

Sorry, I was apparently falling asleep when I wrote that. Wanted to clarify that you need either an add-in card or *motherboard* with a Thunderbolt pass through, not a monitor with one.