2015 15" Dell Precision 7510 (Q M1000M) [6th,4C,H] + GTX 1080 Ti @32Gbps-M2 (ADT...
 
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2015 15" Dell Precision 7510 (Q M1000M) [6th,4C,H] + GTX 1080 Ti @32Gbps-M2 (ADT-Link R43SG) + Win10 1803 // compares M.2 vs TB3 performance  

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nando4
(@nando4)
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Joined: 4 years ago
 

There is no denying that a TB3 eGPU can dramatically improve application processing speed as can be found by many examples on this forum. Gaming on the side then being an extra bonus.

Question then, if your primary use case is gaming is a TB3 eGPU worth it? In this build we compare performance between a M.2 versus TB3 eGPU attached to a single system (identical specs, OS, system build) to help answer that question. The M.2 eGPU being a maximum performance reference before Thunderbolt 3 transport layer encoding is applied.

 

 

System specs (model inc screen size, CPU, iGPU, dGPU, operating system user which eGPU is being used)

  • 2015 15" Dell Precision 7510
  • Intel i7-6820HQ (max 3.6Ghz 4-core with unlocked multis)
  • 16GB RAM (2x8GB, dual channel)
  • Intel HD530 iGPU + Nvidia Quadro M1000M dGPU
  • 2.5" SATA drive bay for primary boot drive, though OS build used was booted off a WinToGo USB NVME SSD
  • M.2 (NVME SSD) slot is free for M.2 eGPU use
  • Windows 10 Professional 1803

 

eGPU hardware (eGPU enclosure, video card, any third-party TB3 cable, any custom mods)

  • ASUS Nvidia GTX 1080 Ti Turbo, flashed with EVGA FTW3 vbios. Has 6P + 8P PCIe power.
  • ADT-Link R43SG (50cm) M.2 eGPU adapter
  • 2 x 220W Dell DA-2 AC adapters 1st powers 75W slot + 75W 6P with cable (1). 2nd powers 150W 8P using cable (2)
    - cable (1) a 8P to 6P+8P power splitter cable supplied with the ADT-Link R43SG
    - cable (2) a 6P to 8P PCIe extender with power-on split-pin/paper-clip as shown here and here
  • M.2 protect board - protects M.2 slot being damaged from repeated insertions

 

To use the ADT-Link R43SG as a TB3 eGPU add the following, making it equivalent to a ADT-Link R43SG-TB3 kit:

 

Hardware pictures (note: require 5+ posts for “attach files” button to appear. Or can link from say http://imgur.com )

underside cabling


GPU power cabling


Left: Connecting ADT-Link R43SG as a TB3 eGPU using JEYI Leidian NVME-to-TB3 enclosure, Right: It's TB3 identification

 

Installation steps (what did you do to get it all going?)

The M.2 and TB3 eGPUs are functionally equivalent in use aspects apart from the latter supporting hotplugging and of course performance discussed in the Benchmarks section below.

Nvidia Optimus accelerated internal LCD mode engages for both. Neither interface saw any system instability.

If considering Hackintoshing, a M.2 eGPU is detected and appears on the PCIe BUS and with correct drivers can be made to work. Eg: this GTX 1080 Ti has macOS 10.13.6 or earlier Nvidia web drivers. A TB3 eGPU isn't so easy. TB3 on a Hackintosh requires SSDT/DSDT mods to emulate the Mac's native TB3 interface as has been done on Dell XPS 95xx systems. While TB3 peripherals work there I've yet to see working TB3 eGPU.

 

Benchmarks (all at FHD 1920x1080 )

Dell Precision 7510M2-extTB3-extdifference M2-intTB3-intdifference
Forza Horizon 410570-33.3%9064-28.9%
Firestrike (gpu)2819621752-22.9%2425418239-24.8%
Heaven145.7117.6-19.3%132.8100.8-24.1%
Valley137.4122.0-11.2%130.2112.1-13.9%
Superposition60245709-5.2%59655470-8.3%
Far Cry 59389-4.3%8678-9.3%
 
AIDA64 write (MB/s)28862160-25.2%
hwinfo64 PCIe portport 9port 5

 

The first two results show a > -22% difference. Why?

Even though this site refers to TB3 as 32Gbps-TB3 (it's electrical link), Intel does disclose the TB3<->TB3 link is 22Gbps. So then let's gather those same benchmarks with greatest difference and run them on a 16Gbps-M2 interface. We'd expect then "22Gbps" TB3 to outperform 16Gbps-M2.

 

Dell Precision 751032Gbps-M232Gbps-TB3difference 16Gbps-M232Gbps-TB3difference
Forza Horizon 410570-33.3%7470-5.4%
Firestrike (gpu)2819621752-22.9%2703421752-19.5%
 
AIDA64 write (MB/s)28862160-25.2%14612160+47.8%
hwinfo64 PCIe portport 9port 5port9port 5

 

Performance Analysis

Forza 4 has a significant 33.3% decrease in FPS, beyond what we'd expect given TB3's 25.2% decrease in AIDA64 bandwidth (H2D). Oddly, even a 16Gbps-M2 interface with supposedly less bandwidth outperforms TB3. TB3 should be just an encode/decoding PCIe transport pair so why are we seeing such a performance decrease over TB3?

We find clues as to why by using the bandwidthTest.exe tool included DaVinci Resolve, running commandline below while with the eGPU connected on a 32Gbps-M2, 32Gbps-TB3 and 16Gbps-M2 interface.

C:\Program Files\Blackmagic Design\DaVinci Resolve\bandwidthTest.exe --htod --mode=shmoo --csv > out.csv

We then review the gathered bandwidth versus block size information where we see:

 

  1. TB3 reduces the 32Gbps PCIe bandwidth anywhere from 25% to 63.5%.
  2. The greatest reduction occurs on small block sizes. 2kb seeing the greatest 63.5% reduction.
  3. TB3 is outperformed by 16Gbps-M2 up to 8kb block size, only matching performance at 16kb block size and outperforming it thereafter.
  4. It appears that Forza 4 is bandwidth bound and utilizes small block transfer sizes.
  5. The min 25% reduction occurs at a block sizes of 200kb and greater -> TB3 is performance optimized for large block sizes.

 

Comments (eg: how has the eGPU improved your workflow or gaming)

Is a TB3 eGPU worth if for gaming? We've shown the additional TB3 transport layer decreases x4 3.0 32Gbps bandwidth anywhere from 25% to as much as 63.5% with bandwidth bound apps/games registering this performance reduction. . The reference 32Gbps-M2 interface itself is 4 times less bandwidth than an Intel desktop.

Is the problem simply the TB3 controller being clocked too slow? Maybe. We do see that TB3 is optimized for large block sizes as used for data transfer on SSDs. Intel certainly have plenty of room to improve this small block transfer performance in TB4.


Q: How to maximize gaming performance on a notebook?

From this build and performance analysis we can suggest:

  • seek a notebook with a decent dGPU
  • seek a candidate system offering a factory direct PCIe eGPU interface like a Alienware Graphics Amplifier port
  • cobble together a eGPU using the NVME SSD's M.2 slot, also a direct PCIe eGPU interface, like shown in this build
  • obtain a TB3 eGPU now knowing it's performance limitations on bandwidth-bound games/apps

 

What are the pros and cons of a M.2 eGPU over Thunderbolt 3 (TB3)?


M.2 eGPU pros over TB3:

1. gets full x4 3.0 bandwidth - TB3 has 25%-64% less H2D/write bandwidth than M.2

2. noticably lower cost for eGPU adapter hardware

3. being able to utilize the eGPU in a macOS Hackintoshed system


M.2 eGPU cons over TB3:

1. require a candidate notebook with dual-storage (M.2 + M.2 or M.2 + SATA) to be viable (use M.2 slot for the eGPU and other storage for boot OS)

2. requires underside eGPU cabling to the internal M.2 port

3. requires DIY tweaking/testing to confirm compatibility

 

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]  


3RYL, Janver Codilan, Sun Changlai and 11 people liked
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itsage
(@itsage)
Illustrious Member Admin
Joined: 4 years ago
 
Posted by: @nando4

Performance Analysis

Forza 4 has a significant 33.3% decrease in FPS, beyond what we’d expect given TB3’s 25.2% decrease in AIDA64 bandwidth (H2D). Oddly, even a 16Gbps-M2 interface with supposedly less bandwidth outperforms TB3. TB3 should be just an encode/decoding PCIe transport pair so why are we seeing such a performance decrease over TB3?

We find clues as to why by using the bandwidthTest.exe tool included DaVinci Resolve, running commandline below while with the eGPU connected on a 32Gbps-M2, 32Gbps-TB3 and 16Gbps-M2 interface.

C:\Program Files\Blackmagic Design\DaVinci Resolve\bandwidthTest.exe --htod --mode=shmoo --csv > out.csv

We then review the gathered bandwidth versus block size information where we see:

 

  1. TB3 reduces the 32Gbps PCIe bandwidth anywhere from 25% to 63.5%.
  2. The greatest reduction occurs on small block sizes. 2kb seeing the greatest 63.5% reduction.
  3. TB3 is outperformed by 16Gbps-M2 up to 8kb block size, only matching performance at 16kb block size and outperforming it thereafter.
  4. It appears that Forza 4 is bandwidth bound and utilizes small block transfer sizes.
  5. The min 25% reduction occurs at a block sizes of 200kb and greater -> TB3 is performance optimized for large block sizes.

 

Thank you for sharing this amazing analysis of performance difference!

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2020 15" HP Spectre X360 [11th,4C,G] + RTX 2080 Ti @ 32Gbps-TB4 (AORUS Gaming Box) + Win10 2004 [build link]  


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Eightarmedpet
(@eightarmedpet)
Noble Member Moderator
Joined: 4 years ago
 

Isn’t Forza 4 known for being a game that runs poorly on egpus? Or have I made that up?

2017 13" MacBook Pro Touch Bar
GTX1060 + AKiTiO Thunder3 + Win10
GTX1070 + Sonnet Breakaway Box + Win10
GTX1070 + Razer Core V1 + Win10
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Vega 56 + Mantiz Venus + macOS + W10

---

LG 5K Ultrafine flickering issue fix

 
2017 13" MacBook Pro [7th,2C,U] + RX 5700 XT @ 32Gbps-TB3 (Mantiz Venus) + macOS 10.15.4 & Win10 2004 [build link]  


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nando4
(@nando4)
Noble Member Admin
Joined: 4 years ago
 
Posted by: @eightarmedpet

Isn’t Forza 4 known for being a game that runs poorly on egpus? Or have I made that up?

 

  • Forza 4 is one game that shows a significant peformance drop of 33% FPS run on TB3 rather than a M.2 eGPU interface. Since that is > 25%, from our chart we can say it's small-block bandwidth bound. That is, it's doing block transfers smaller than 200kb where bandwidth reduces by up 63.5%.

 

  • Intel may consider clocking TB4 faster on small block sizes to correct the poor small block performance

 

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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mac_editor
(@mac_editor)
Famed Member Moderator
Joined: 4 years ago
 

@nando4

Thank you for this build. This is exceptionally insightful (and significant) and finally we have some more understanding of ‘where’ performance is lost. Added to my permanent reading list.

purge-wranglertbt-flashpurge-nvdaset-eGPU
Insights Into macOS Video Editing Performance

Master Threads:
2014 15-inch MacBook Pro 750M
2018 15-inch MacBook Pro

 
2019 13" MacBook Pro [8th,4C,U] + RX Vega 64 @ 32Gbps-TB3 (Mantiz Venus) + macOS 10.14.6 & Win10 [build link]  


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nando4
(@nando4)
Noble Member Admin
Joined: 4 years ago
 
Posted by: @mac_editor

@nando4

Thank you for this build. This is exceptionally insightful (and significant) and finally we have some more understanding of ‘where’ performance is lost. Added to my permanent reading list.

Thank you.  There are another two reasons why we are seeing poor TB3 performance, particularly gaming which my 6th-gen i-core Dell 7510 isn't affected by. Here's the three listed for completeness:

1. the slow TB3 small-block bandwidth we describe in the opening post.

2. An uncooled PCH controller on Intel "H" CPU leading to PCH throttling. "U" CPU systems have the PCH on the CPU which is cooled so are unaffected. M.2 eGPUs are also affected. Adding a thermal pad bridge can wick away as a workaround. @itsage has covered this here.

3. Unoptimized BIOS on non-Mac "H" 8th/9th gen CPU systems leading to a further 15% performance degradation. M.2 eGPUs are also affected. A system BIOS type patch is required as a fix.

(2) and (3) are new findings and they strike out our previous suggestion that a 15" MBP delivers superior performance due to their direct TB3 to CPU configuration. Apple has optimized their 15" MBP's TB3 performance. PC vendors like Dell with their XPS 9570 / 7590 have not.

How does (1)-(3) playout for peformance? When using Forza 4, FHD external GTX 1080 Ti as reference we'll get this performance waterfall:

1. 120-130 FPS on a desktop 128Gbps (x16 3.0) system

1. 105 FPS on M.2 eGPU - a 32Gbps M.2 (PCIe) link

2. 70 FPS on a TB3 eGPU - loss due to 25%-63.5% TB3 bandwidth reduction

3. 60 FPS on a TB3 eGPU - a 15% loss from unoptimized BIOS on 8th/9th-gen "H" systems like a Dell XPS 9570 / 7590

 

Halving FPS going to a TB3 eGPU is a steep loss. Wouldn't be surprised it the shocked casual gamer would just return the TB3 gear and stick with a desktop instead.

Anyone connected with Intel is welcome to pass this info along.  I believe we are the first to pinpoint why TB3 underperforms in gaming. Finger crossed they'll fix this in TB4.  Would be in their interests to do so. There might be x4 4.0 Ryzen 4000 M.2 AMD eGPU possibilities on just-announced 8C/16T AMD notebooks [ note: not sure if mobile Ryzen 4000 has PCIe 3.0 or PCIe 4.0 M.2 slots ].

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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Donwey
(@donwey)
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Joined: 2 years ago
 

@nando4 Is there a patch that can be applied for unoptimized BIOS on non-Mac “H” 8th/9th gen CPU systems? I myself own a dell xps 9560 and havent known about this bios issue. How did you find out? 

Dell XPS 15 9560 @ I7 7700HQ + Aorus Gaming Box GTX 1080 + External Monitor 1440p

 
2017 15" Dell XPS 15 9560 (GTX1050) [7th,4C,H] + GTX 1080 @ 16Gbps-TB3 (AORUS Gaming Box) + Win10 [build link]  


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nando4
(@nando4)
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Joined: 4 years ago
 
Posted by: @donwey

@nando4 Is there a patch that can be applied for unoptimized BIOS .. I myself own a dell xps 9560 and havent known about this bios issue.

Dell XPS 9560 is 7th gen, eg: i7-7700HQ so is not applicable.

If you have a 56Wh-battery XPS 9560 with slot for 2.5" SSD, then can get a tremendous eGPU boost by using the available NVME SSD M.2 slot to host the eGPU using an ADT-Link R43SG. Just like the opening post build.

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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Donwey
(@donwey)
Active Member
Joined: 2 years ago
 
Posted by: @nando4
Posted by: @donwey

@nando4 Is there a patch that can be applied for unoptimized BIOS .. I myself own a dell xps 9560 and havent known about this bios issue.

Dell XPS 9560 is 7th gen, eg: i7-7700HQ so is not applicable.

If you have a 56Wh-battery XPS 9560 with slot for 2.5" SSD, then can get a tremendous eGPU boost by using the available NVME SSD M.2 slot to host the eGPU using an ADT-Link R43SG. Just like the opening post build.

Thank you, i have already ordered ADT-Link R43SG.

I will create a new build with my Dell XPS 9560 and Aorus Gaming Box GTX 1080 and make some gaming benchmarks. Later when i get ADT-Link R43SG i can make comparison of the performance between those two. Although i dont think the performance increase will be that much high. From your benchmarks it seems only some benchmark tools and Forza Horizon 4 are affected but Far Cry 5 is not? I wonder what other games are affected like FH4. 

This post was modified 11 months ago

Dell XPS 15 9560 @ I7 7700HQ + Aorus Gaming Box GTX 1080 + External Monitor 1440p

 
2017 15" Dell XPS 15 9560 (GTX1050) [7th,4C,H] + GTX 1080 @ 16Gbps-TB3 (AORUS Gaming Box) + Win10 [build link]  


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mac_editor
(@mac_editor)
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Joined: 4 years ago
 

@nando4

Thank you for elaborating. I was aware of (2) being an issue previously. Regarding (3), was there a recent system you came across/or on this forum where BIOS updates made the difference? That’s another (important) variable it seems. Do we have before/after BIOS update results which I may have missed? 15% performance difference is significant. 

purge-wranglertbt-flashpurge-nvdaset-eGPU
Insights Into macOS Video Editing Performance

Master Threads:
2014 15-inch MacBook Pro 750M
2018 15-inch MacBook Pro

 
2019 13" MacBook Pro [8th,4C,U] + RX Vega 64 @ 32Gbps-TB3 (Mantiz Venus) + macOS 10.14.6 & Win10 [build link]  


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