Ice Lake CPU on-die Thunderbolt 3 Controller Bandwidth  

@itsage , width your RAID0 throughput exceeding x4 3.0 bandwidth suggests those two TB3 ports on your Ice Lake system are each hosted off separate PCH PCIe ports. Can you post a hwinfo64 screenshot to confirm? 

That would then differ to previous 13/15" MBPs whose dual TB3 ports on left/right were each hosted off a x4 3.0 PCIe port. There you'd need to RAID0 your drives by connecting the TB3 cable to opposite-sided TB3 ports to achieve your Ice Lake TB3 throughput.

@nando4, Thank you for the insight. I will boot into Windows and connect all four ports with Thunderbolt 3 devices and take a screen capture. In the mean time, I found these from a previous build with the 2020 13-in MacBook Pro Ice Lake showing the four Thunderbolt PCI Express Ports.

Posted by: @itsage

In a RAID 0, they nearly double the speed. I tried in both opposing Thunderbolt 3 ports as well as same side. The throughput achieved was the same. 

Hmm? 40Gbps on one side? So 4 controllers on the 2020 Ice Lake macs as @nando4 suggests?

@mac_editor, Sure seems like it to me. Now looking at the screen caps from Device Manager and HWiNFO64, it makes more sense. Each Thunderbolt 3 port has its own x4 PCIe connection rather than two ports to one TB3 controller as before.

@itsage, Dang that's a nice step up then! Though what speed do you get on older TB3 system but connected to different sides/controllers? Are there efficiency improvements vs. previous gen? Because this test doesn't tell us about the shared bandwidth anymore (since its two separate controllers).

@mac_editor, Same test with a 2019 13-in MacBook Pro results in a 23Gbps cap. This was both through opposing side and same side TB3 ports. Next question is what happens when there's a RAID0 with 4x NVMe drives on the Ice Lake system? Unfortunately I don't have anymore M2-TB3 enclosures to test. Although I can use a regular TB3 enclosure with an M.2 PCIe adapter.

Posted by: @itsage

@mac_editor, Same test with a 2019 13-in MacBook Pro results in a 23Gbps cap. This was both through opposing side and same side TB3 ports.

 

AN unexpected result. Almost as if the 2xTB3 controllers are reserving the 10Gbps USB-C Gen2 bandwidth. Or is that because of the DMI bottleneck with 8th-gen or older U processors that's been adjusted in 10th-gen?

As an aside, can you do the same RAID0 test with a 15-inch MBP with 9th/8th-gen H CPUs using opposing sided TB3 ports? Their TB3 ports connect to the CPU so have no DMI bottleneck and should match or exceed the performance seen with these 10th-gen U CPUs.

@nando4, Here are the results on 2019 16-in MacBook Pro.

Posted by: @itsage

Next question is what happens when there's a RAID0 with 4x NVMe drives on the Ice Lake system? Unfortunately I don't have anymore M2-TB3 enclosures to test. Although I can use a regular TB3 enclosure with an M.2 PCIe adapter.

Intel have certainly improved the TB3 controller in Ice Lake CPUs. Though do we get the full burrito?

Yes, please use the regular TB3 enclosure with M.2 adapter to wired up 4x NVME drives. We'll then see if there is a full FAT 4x TB3 pipe or if DMI applies some brakes.