XPS 15 - 9550 not able to reach 40Gbps over TB3?
 
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[Solved] XPS 15 - 9550 not able to reach 40Gbps over TB3?  

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Splitframe
(@splitframe)
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March-2016>> Dell now are listing TB3 PCIe lanes per XPS/Precision model in an official document


Feb-2017 nando4>> Dell have certainly been made aware of the problem as their latest XPS 9560 specs now explicitly state "Thunderbolt 3 (2 lanes of PCI Express 3)". REF: 
http://www.dell.com/au/p/xps-15-9560-laptop/pd

Ports & Slots

1. SD card slot | 2. USB 3.0 with PowerShare | 3. Battery gauge button and indicator | 4. Kensington lock slot | 5. AC power | 6. HDMI |7. Thunderbolt™ 3 (2 lanes of PCI Express Gen 3) supporting: Power in/charging, PowerShare, Thunderbolt 3 (40Gbps bi-directional), USB 3.1 Gen 2 (10Gbps), Native DisplayPort 1.2 video output, VGA, HDMI, Ethernet and USB-A via Dell Adapter (sold separately) | 8. Headset jack

 

3-Jan-2017 nando4>> The conclusion of this problem is the Dell XPS 9350/9360/9550/9650 and Precision M5510/M5520 have 2 PCIe 3.0 lanes (16Gbps), wired rather than 4 PCIe 3.0 lanes (32Gbps). This is summarized at https://egpu.io/forums/pc-setup/xps-15-9550-not-able-to-reach-40gbps-over-tb3/paged/3/#post-979 and the post straight after it.

 


 

Hi,

I noticed that all devices I connect via the AKiTiO Thunder3 PCIe under perform by about 50% so I got curious and contacted AKiTiO about this issue.

They only had an XPS 13 9350 and said that in the XPS 13 the TB3 controller definitely only connected with x2.3 ( 16Gbps ) and that the HWInfo64 screenshot I send from my XPS 15 looks exactly the same as theirs on the XPS 13.

According to HWInfo64 the XPS 15 is indeed equipped with an DSL6340, so is the controller hindered by it's x2.3 or x4.2 pcie connection? Is it a hardware or software ( BIOS/Firmware ) issue?

 

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nando4
(@nando4)
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Yup. Root bridge (port#15) is reporting x2 3.0, which will be 16Gbps. Without eGPU attached does it still report x2 3.0?

If so, that would be a Dell issue with their handshaking with the TB3 controller. If you look at the TB3 controller, is it connected at x4 3.0 to the videocard? I only see a Samsung SSD there. Maybe it runs at x2 3.0 and the uplink bridges are downgraded in speed?

Those XPS machines are very nice. Want full TB3-32Gbps eGPU link speed on them

eGPU Setup 1.35    •    eGPU Port Bandwidth Reference Table

 
2015 15" Dell Precision 7510 (Q M1000M) [6th,4C,H] + GTX 1080 Ti @32Gbps-M2 (ADT-Link R43SG) + Win10 1803 [build link]  


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Splitframe
(@splitframe)
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The pic above is with the 960 pro in the Akitio, with the NVidia it's exactly the same just with the GPU and the HDAudio thing in the spot where now the 960 pro is.

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nando4
(@nando4)
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Dell XPS 9550 and Precision M5510 run a x2 3.0 PCIe (16Gbps) hosting the TB3 controller limiting performance to 16Gbps

Your CUDA-Z results:   http://imgur.com/a/CIBQJ

Yep.. bandwidth is definitely x2 3.0. Couple of folks have posted CUDA-Z output from Apples running x4 3.0. It's double yours.

The problem here is the BIOS has not configured the ports correctly as can be seen in the snippet pic below from  pg 197 of http://www.intel.com/content/dam/www/public/us/en/documents/datasheets/100-series-chipset-datasheet-vol-1.pdf

- 2 x2 links:  port13 + port15   <-------- yours
- 1 x4 link:  port13     <------------------  what you want

 port15 may be electrically excluded if configured to run x4 on port13

You only have one Thunderbolt port which is hosted of port15. Now the question is can port15 be mapped back to port13? Or is it still hardwired as port13, port15 (like it was in all previous chipsets up to 4th gen i-core) so that setting x4 port13 would exclude port15 from being active? 

If the latter, then it's a hardware limitation requiring a new systemboard and I can see Dell snaking around to avoid that, because by right, they fix or give you a refund for misadvertising.  If it's the former, then Dell can release a new BIOS setting port13 to x4.

It would be a pretty big oversight to wire up only 2 lanes from the Intel chipset to the 4-lane TB controller. So fingers crossed, it will just be a BIOS fix.

The Precision M5510 lspci.txt output here shows it too has a port13+port 15 x2 3.0 configuration matching what we see with the XPS 9550.

In this thread we show XPS 9350/9360/9550 and Precision M5510 all run 16Gbps TB3 (half advertised)

 

eGPU Setup 1.35    •    eGPU Port Bandwidth Reference Table

 
2015 15" Dell Precision 7510 (Q M1000M) [6th,4C,H] + GTX 1080 Ti @32Gbps-M2 (ADT-Link R43SG) + Win10 1803 [build link]  


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Splitframe
(@splitframe)
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Many thanks to you nando!

I will throw the Dell support a mail explaining the situation, I hope they can just change the mapping
in the BIOS...

At least I can now be certain that there is a problem.

Thanks.

 

Posted by: nando4

 

You only have one Thunderbolt port which is hosted of port15. Now the question is can port15 be mapped back to port13? Or is it still hardwired as port13, port15 (like it was in all previous chipsets up to 4th gen i-core) so that setting x4 port13 would exclude port15 from being active? 

 

   

 Is there a chance that I can try this with Setup 1.31?

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nando4
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Unfortunately no.

As of Series-6 (2nd gen i-core), lane width is a write-once ME FW bootstrap thats asserted before any software or bootloader loads. I only know @timohour with a 3rd gen i-core Dell e6430 who extracted the BIOS+MEFW, used fitc (Intel tool) to change the lane width, then flashed the BIOS+MEFW back. He had to jumper the audio chip to enable full bios r-w. He got a x2 2.0 eGPU working thiss way. This is a fairly technically challenging process that may not even apply to your system. Intel has been locking down more configuration options each generation.

I'd suggest go the Dell route. There can be no denying now there is a BIOS/hardware misconfiguration resulting in only 16Gbps (x2 3.0) PCIe bandwidth instead of 32Gbps (x4 3.0) that Thunderbolt3 is specced at.

 

 Is there a chance that I can try this with Setup 1.31?   

 

eGPU Setup 1.35    •    eGPU Port Bandwidth Reference Table

 
2015 15" Dell Precision 7510 (Q M1000M) [6th,4C,H] + GTX 1080 Ti @32Gbps-M2 (ADT-Link R43SG) + Win10 1803 [build link]  


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Splitframe
(@splitframe)
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That's obama.

Well I'll keep you guys posted on Dells answer to this.

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rhx123
(@rhx123)
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Unfortunately same issue on XPS 13 9360.

But it seems to be on port 1.

XPS 13 9360 + Acer Graphics Dock


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Splitframe
(@splitframe)
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Posted by: Richard

 

Unfortunately same issue on XPS 13 9360.

But it seems to be on port 1.

   

Aww man... thanks for the info.
Can you run CUDA-Z anyway and tell us what values you get on the performance tab?
Thanks.

To do: Create my signature with system and expected eGPU configuration information to give context to my posts. I have no builds.

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itsage
(@itsage)
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I picked up a XPS 13 9350 this past weekend. I will check for the link speed tonight when I hook it up to Thunder3 enclosure and report back.  

external graphics card builds
best laptops for external GPU
eGPU enclosure buyer's guide

 
2013 Mac Pro (FP D500 x2) [3rd,12C,E] + RX 5700 XT @ 16Gbps-TB2>TB3 (Mantiz Saturn Pro) + macOS 11 [build link]  


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