Buyer's Guide: "port’s use impinges on eGPU PCIe bandwidth"
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Buyer's Guide: "port’s use impinges on eGPU PCIe bandwidth"  


Estimable Member
Joined: 4 years ago

I'm referring directly to this quote from the Buyer Guide:

port’s use impinges on eGPU PCIe bandwidth, except for (i) Displayport devices (ii) XG Station 2 whose ports are hosted via a separate USB switch & USB-B cable

I just realized that due to the way Intel handles ThunderBolt 3 (throttling PCIe to 22Gbps on full links, to reserve 10Gbps for USB and 8Gbps for DP), there SHOULD be virtually no performance degradation if using the USB ports, or if any of the enclosure's additional ports (i.e. internal SATA) are part of the USB hub. Anyone care to comment?

2016 15" HP ZBook 15 G3 [Xeon E3-1545M, Iris Pro p580, no dGPU] + GTX1070@32Gbps-TB3 (Aorus Gaming Box) + Win10pro

2018 15" HP ZBook 15 G5 (Q P1000) [8th,6C,H] + GTX 1070 @ 32Gbps-TB3 (AORUS Gaming Box) + Win10 [build link]  

Noble Member Admin
Joined: 5 years ago

 The enclosure TB3 USB-C 3.1 controller hosting the additional ports is a PCIe device as shown here. Therefore it too becomes part of the "up to 4 lanes of PCIe 3.0" input to the TB3 controller combing traffic with the video card. Therefore these extra enclosure ports do impinge on the TB3 channel video card bandwidth.

Performance enthuasiasts may then choose to get an enclosure without those extra ports and host high bandwidth devices such as storage off it's own separate host port and cable as a USB-C 3.1 or USB 3.0 device.


More details at Enclosure ports can decrease TB3 eGPU bandwidth by up to 31.2%

eGPU Setup 1.35    •    eGPU Port Bandwidth Reference Table

2015 15" Dell Precision 7510 (Q M1000M) [6th,4C,H] + GTX 1080 Ti @32Gbps-M.2 (ADT-Link R43SG) + Win10 1803 // compares M.2 vs TB3 performance inc unoptimized H-CPU BIOS [build link]  

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