Asus Thunderbolt Ex 4 and Corning Optical cable -- USB not working

The goal

My office is upstairs, and my server closet is downstairs. My goal is to move my gaming PC from my office to my server rack. I have a ~18m ethernet line run. I would like to replace that with the 25m corning thunderbolt cable.

My attempts include Caldigit TS4, Corning Optical TB 25m, and Asus Thunderbolt Ex 4. The results are strange.

Current state

Using the caldigit ts4 cable everything works. Full stop. It all works. Mac, PC, BIOS controls, displays, USB ports, L1kvm.

Using the corning cable with the PC:

  1. The caldigit dock - the BIOS screen doesn’t show up, I see nothing until Arch boot messages, but the DP connections work in the OS, none of the USB ports on the dock connect to the computer at all, I tried unplugging the l1kvm USB connection and direct connecting the TKL dongle to the dock - no dice
  2. The belkin dock - the dock flickers on and off and no signal comes through

Using the corning cable with the Mac:

  1. The caldigit dock - everything works, displays uqhd@160 + qhd@120, USB ports, everything except power. I have to keep the lid open though, I can close it if I’m using the TS4 cable (I suspect that’s power related, I haven’t tried to fix it)
  2. The belkin dock - untested, I’ll try this later

The setup:

PC

  • Motherboard: Asus Tuf Gaming x670e plus wifi
  • CPU: 7950x3d
  • AIC: Asus Thunderbolt Ex 4
  • BIOS – USB4: on, No Security, Full Resources; CSM: off; IOMMU: on; SVM: on; Fastboot: off
  • OS: Arch Linux (I tried windows too with the same results)
  • Dock: CalDigit TS4

Mac

  • 2021 M1 Pro
  • Dock: Belkin Thunderbolt 3 Dock Plus

L1KVM DP1.4 2x2 5gb

  • USB: front G915TKL dongle, back 4 port USB3 hub → Arctis Pro Wireless, Razer Kiyo, Logitech powerplay mat
  • Monitors: LG34GN850B (uqhd@160), S2417DG (qhd@120)
  • Docks
    • 2x DP1.4 + USB3.0 B to C → Belkin
    • DP1.4 + DP to USB C + USB3.0 B to C → CalDigit

An aside, the POST times for the Asus motherboard are super slow (from 30s up to 1 minute at times just to BIOS screen). I’m wondering if a GC Maple Ridge on a Gigabyte MB would be a better option, but would it just be the same rigamarole of things not working? Other posts in this forum imply Gigabyte is worse than Asus for TB.

I decided to get a CalDigit TS3 to try it out, and it behaves the same as the TS4+Corning pairing interestingly. That makes me think the corning cable is forcing a tb3 connection, and the issue lies in the Thunderbolt Ex 4 card interfacing with tb3 accessories.

For posterity I think I found the issue though I can’t confirm. lspci -vvv was showing the Asus thunderbolt card was in nopcie mode. I believe the problem is that the tbt card was installed in an x2 pcie slot rather than an x4 slot. My rudimentary interpretation of CalDigit responses on reddit is that the USB and Ethernet on the ts4 go through pcie. I can’t quite confirm though since my graphics card covers the x4 slot, and I don’t feel like rebuilding it in the Asus board to try it with the APU.

I’m returning the Asus board and aic and swapping for gigabyte to try that since their x4 slot is further down on the motherboard.

Reporting back on this. I tried a Maple Ridge card with a x670 Aorus Elite AX and had the same problems.

I was able to make it work with the Aorus Elite AX board using a Titan Ridge rev2 card and a CalDigit TS3. Thunderbolt 3 works with the Corning cable, but any thunderbolt 4 parts seems to cause instability.

@aravance did you reach out to Corning about this? I have a 15m version of the same cable and I’m about to take a journey in to solving a similar problem. I thought I read somewhere that TB3 <> TB4 cables should be backward compatible.

Hi,

i run a similar setup and it works great for me. i struggled also a lot with AMD back then it was AM4.

i have now my gaming PC (Intel + Asus Board with EX4) down in the basement and running a 25meter corning cable to the second floor. There i have a “old” Belkin TB3 Dock, after i tested about 4 different docks it runs with that one the best.

i start the computer over my App on the Iphone ( WOL) i will be able to use mouse and other peripherals right at the start, even enter the BIOS is working. i have two screens connected ( 2540x1440@144Hz and 3440x1440@100Hz) full functional including G-Sync.

i would like to tyr it again with AMD and the new AM5 Platform but i’m afraid, that it will breake my corning setup again. Maybe it better works with B650 Asus Board, since someone else here had success.

@aravance just try this board: TUF GAMING B650-PLUS, you need to install the EX4 Card in the second x16 slot which is on the bottom

@KoSoVaR I reached out to CalDigit, and they said they’ve gotten multiple reports of flakiness with the Corning cables and the TS4, but they said the TS3 has worked consistently. I haven’t heard back from Corning.

@Martin_Looter_King I got AM5 working with this setup: x670 Aorus Elite AX with Titan Ridge Rev 2.0 in slot2 (w/ a trendnet SFP+ card in slot3), and the dock is a CalDigit TS3+.

I wound up swapping the x670 Elite AX for an x670e Xtreme for the built in 10g ethernet, and everything still works great, but that’s not required. I’m kind of curious if the TS3+ would still work with the Gigabyte Maple Ridge card, but I already returned all the excess parts after I got it working.

BIOS works over the tb dock, but I do have one weird thing. When I have the thunderbolt card plugged in, I can’t do a bios upgrade on the motherboard. It accepts the file, goes to reboot, then after reboot acts like no upgrade is in progress. It kind of seems like it’s related to the f20a bios usb handling. I may have to unhook thunderbolt to do a bios upgrade then put it back.

i did try out multiple solution with tb. Mostly corning do work really fine and they are tb3 cable. As for the add on card… they are add-on card. Cable are made to be plug directly to thunderbolt port. Try over a laptop or a proper pc with a tb port… like asrock or so. not passing by an kind of emulating extender… we got problem and ditch long time ago those extra pci-e card.

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