5K Ultrafine 1st gen via 1x DP 1.4 ?
To answer the title, "5K Ultrafine 1st gen via 1x DP 1.4 ? " sure that's possible, you need an DP 1.4 MST hub (Club 3D CSV-7300, Cable Matters 201365 which I happen to own) to split the signal and then feed it to a riser powered Gigabyte Alpine/Titan Ridge GC https://egpu.io/forums/builds/late-2018-mac-mini-wx-910032gbps-tb3-mantiz-venus-thunderbolt-3-monitor-output-macos-10-14-1-itsage/
Lenovo ThinkPad 25 -- GALAX SNPR TB3 1060 -- Lenovo Graphics Dock -- Benq BL2411PT - - two PackedPixels - Dasung not-eReader backer
@chx, I did that last year: https://egpu.io/forums/thunderbolt-enclosures/list-of-intel-titan-ridge-thunderbolt-3-devices/paged/6/#post-59604
Use one DisplayPort 1.4 output of GPU to get 5K from the LG Ultrafine 5K. The purpose of that is to save a DisplayPort of the GPU. The DisplayPort 1.4 MST hub I used was the one inside a HP Thunderbolt Dock G2. There's also the Delock 87737.
But the purpose of this thread is not to save a DisplayPort output of the GPU. The limitation discussed in this thread is that the motherboard only has one DisplayPort 1.4 input.
If a GC-TITAN RIDGE is used then you might as well just connect two DisplayPort outputs from the GPU directly to the GC-TITAN RIDGE (skipping the MST hub) to get 5K from the LG UltraFine 5K. If the GC-TITAN RIDGE is not in a PCIe slot of the motherboard, then the PCIe features of the display cannot be used (USB, etc.).
Dual HBR2 has more bandwidth than HBR3 so it can support 10 bpc instead of 8 bpc.
But newer DisplayPort 1.4 MST hubs (not the HP Thunderbolt Dock G2 - but maybe it can after a firmware update?) and GPUs (Navi/RTX) support DSC so they could allow 10 bpc also.
I’ve actually built the sffpc, and the UltraFine works! I’m actually shocked at how well. All features work in both macOS and windows 10 but as predicted the display is only at 4K, which still looks great.
2017 13" MacBook Pro Touch Bar
GTX1060 + AKiTiO Thunder3 + Win10
GTX1070 + Sonnet Breakaway Box + Win10
GTX1070 + Razer Core V1 + Win10
Vega 56 + Razer Core V1 + macOS + Win10
Vega 56 + Mantiz Venus + macOS + W10