eGPU Performance Loss - PCI Express vs. Thunderbolt  

Thanks for the tests! So with an iMac late 2013 with TB1, a GTX 1060 should have the same Performance like a GTX 1080?

@Gotsche - No, 1080 will performance better, here we test the performance drop of the GPUs!

With your iMac you will use External Display (Monitor) so go with 1080 if you can

01. 1060 (eGPU) vs. 1080 (eGPU) Internal Display test on 2016 MacBook Pro 13"

02. 1060 (dGPU Laptop) vs. 1080 (eGPU) External Display test with 2016 14″ Razer Blade

GTX 1060:

GTX 1080:

I want to use the internal display of the iMac because of no room for another Display... - the iMac is placed (removeable) at the dining table. No own room anymore since the child was born.

So - with the many problems and internal/external Display barriers (I'll Need to run windowed-mode games to get the eGPU Performance without an external Display - because I don't have an iGPU), I've a new plan:

If the external displaymode of my iMac works with TB3<->TB2/TB1 Adapter between iMac and a TB3-PC, I'll buy a gaming mini-PC with USB-C Interface to connect it to the Display of the iMac. If this  is working, I'm done. Advantages: full Performance of the PCIe Interface of the GPU. No bad Drivers and crazy modes... A mini-gaming-PC is not much bigger as the Akitio Node. Only the displayportinterface between the iMac and a PC. I'll test it...

AKiTiO Thunder2 + EVGA GTX 1060 6GB SC + MacBook Pro (Retina, 15-inch, Later 2013) – Thunderbolt2 (16Gbps) Test:

GTX 1060 6GB in Desktop PC (PCIe slot 126Gbps)

GTX 1060 6GB in eGPU Thunderbolt 2 (16 Gbps) External Display: -16% performance drop

 GTX 1060 6GB in eGPU Thunderbolt 2 (16 Gbps) Internal Display: -24% performance drop

According to my opinion the gap is less then 17% because the difference in terms of cpu performance between desktop environment and laptop one affects this kind of benchmark.

Most of the eGPU users wants GTX 1080Ti, thanks to @konceptz we can see that we have -20% performance drop of the GPU on external display, on the Internal Display we have only macOS benchmarks but -35% performance drop was expected even for Thunderbolt 3!

GTX 1080Ti 11GB in Desktop PC (PCIe slot 126Gbps)

AKiTiO Node + GTX 1080Ti FE 11GB / MacBook Pro (Retina, 15-inch, Late 2016) Thunderbolt3 (32Gbps) External Display: -20% performance drop

Mantiz Venus + GTX 1080Ti FE 11GB / MacBook Pro (Retina, 15-inch, Late 2016) Thunderbolt3 (32Gbps) Internal Display: -35% performance drop

We have full tests with GTX 1060 6GB on all Thunderbolt ports vs. Desktop PC & Gaming Laptop:

Even on TB1 - External display it's still preforming great. Nothing to worry about!

I want to add some videos that confirms my tests:

This is a comparison between eGPU with GTX 970 (External Display) performance vs. desktop performance (GTX 970):

eGPU Internal vs External display comparison - GeForce GTX 1060 - Star Wars Battlefront

eGPU Internal vs External display comparison - GTX 970 -  The Division

eGPU with GTX 970 VS eGPU with GTX 1060 VS eGPU with GTX 1070 (External Display)

An other interesting thing to explore is the performance drop is influenced by architecture (Pascal vs Maxwell).

Is worth to buy an old 980 or a 1060 ? The amount of dram vram is a variable that increases the drop ?