2015 Gigabyte X99 Designare [5th,6C,K] + Radeon VII @ 32Gbps-TB3 (Mantiz Venus) + Win10 1809 [itsage]
I'm planning on doing another dGPU vs. TB3 eGPU comparison with this x99 Thunderbolt 3 system. The last time I did this test was almost two years ago with a GTX 980 Ti. The dPGU tests will be run at x16, x4, and x2 PCIe 3.0 speed. The eGPU tests will be run at x4 and x2 PCIe 3.0 over Thunderbolt 3 speed. I'm using the Gigabyte X99 Designare EX motherboard because it's one of the very few that not only has an on-board Thunderbolt 3 port but also attaches the Thunderbolt 3 controller directly to the CPU.
Gigabyte GA-X99 Designare EX - i7-5960X/Radeon VII dGPU & eGPU/16GB RAM/480GB SATA SSD
When this motherboard first came out in 2016, the Thunderbolt 3 firmware was not certified. I had to install the firmware update from Gigabyte Support website to enable Thunderbolt 3 functionality. It's currently running Intel Thunderbolt Software version 184.108.40.2060. BIOS settings allow me to enable Thunderbolt GFX support. It doesn't work through hot-plug though. I always need to connect the eGPU prior to booting up the system. Both Nvidia and AMD eGPU can work without error 12.
You may notice GPU-Z is showing less than full Thunderbolt 3 speed. This has been a puzzle I've yet to solve. I had this very same system working at full 22Gbps Thunderbolt 3 speed before. After Windows and/or BIOS updates, the Thunderbolt 3 PCIe link somehow runs at x2 rather than x4.
Looking back at my screen captures from when this motherboard was running at full TB3 speed, it seems ASPM had something to do with the half speed. I changed Power Platform Management settings in the BIOS but it made no difference.
I also tried different solutions to disable ASPM in Windows 10 but no success. Here's a failed attempt through Registry Editor.
Will update once ASPM L1 Entry issue is resolved.
I currently have the i7-5960X overclocked to 4.3 GHz. XMP profile is enabled for memory modules to run in quad-channel DDR4-3200 MHz. This ASPM settings seems to effect internal PCI Express performance as well. I'd greatly appreciate any input you may have in order to disable this feature.
Could it be that the slot or AIC is damaged, so that they can't negotiate x4? Test a different x4 or greater card in the slot. Test the AIC in a different x4 or greater slot.
I know the PCI commands to change the link speed while the computer is running but I don't think there's a way to change the link width.
@joevt3 This is an on-board USB-C port with Thunderbolt 3. There's a THB_C header to use an AIC but I prefer the direct Alpine Ridge controller to processor connection. I had this same motherboard running at full 4 lanes before. I looked through more screen captures and even found one with ASPM L1 Entry active but ran at full TB3 speed.
Have you tried completely clearing the cmos and resetting everything? I had all sorts of issues when I first set up TB3 on my X99 deluxe/ThunderboltEX II including rendering the board unable to post, once I completely reset the cmos using the reset button/jumper I got things working.
Even after the reset I did have a similar issue with the card running at x2 width, I ended up needing to physically move the card to get full x4 connectivity, which is obviously not an option for you. This is all with a fairly old Motherboard BIOS, I didn't want to break my OC and have to re-validate it, I did update the TB3 Firmware and drivers to the most recent available from ASUS.
Interestingly enough, the Intel TB control panel tells me EGPU is not supported, but aside from POST/Pre-boot screens it works fine, can even be hotplugged with the system running headless.
@ningauble77 I cleared CMOS as well as attempted downgrading/upgrading the BIOS to different versions but nothing changed. It's something with the motherboard itself. Only the top x16 would work with the dGPU was another sign there's a malfunction somewhere.
Fortunately I have a backup ASUS X99 Deluxe II which comes with the EX3 AIC. I did the swap this morning and got full TB3 speed now! ASUS BIOS actually provides the ability to switch between Northbrigde and Southbridge routing for the AIC. I'm using the CPU connection for now because that's the best option. I will switch to PCH later on to check the difference.