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> Benchmarks show the difference to desktop even when using only 16Gbps Thunderbolt [...] to drive an external display is below 20%.

Average FPS benchmarks can be misleading, intermittent stutters can severely impact perceived performance without necessarily reducing the average FPS by much.

More rigorous testing shows that eGPUs can cause pretty severe stuttering: https://www.pcper.com/reviews/Graphics-Cards/External-Graphi...

I was just going to say I never experienced any performance issues using a Gigabyte eGPU with the latest MBPro as well as an Intel 7th gen NUC. For $699, it’s the cheapest way to get “desktop like GPU performance” on a laptop or small factor PC.

> Sandy Bridge, on the other hand, both in laptops like the ThinkPad T420 and X220 (which still have the best keyboard on any laptop) and off lease HP/Dell workstations sporting high frequency Xeons are an astonishing price/value bargain (the cheapest E3 1270 workstations with motherboard, CPU, cooler, chassis and PSU are about the same cost as the roughly equivalent i5 7400 CPU alone). Yes, the wattage has dropped significantly but the IPC only grew by 20% from Sandy Bridge to Kaby Lake

The older laptops are fine if you are looking for something you can plug in and work on, and have fairly minimal requirements for a GPU. The newer laptops are much better for those who want to compute on the go, without being tethered to a wall plug, and have made huge strides in graphics capabilities/efficiency.

This is compounded by old/failing batteries and the fact that it's nigh-impossible to source high-quality aftermarket replacements. Most of the aftermarket batteries on eBay/Amazon will have cells start to die or drift out of balance within a month or less. Really the only option seems to be to buy the OEM part... but even from someone like Amazon it could be contaminated by commingling. There is a widely-acknowledged gap in the market here that some startup could exploit.

Going from a W510 with Nehalem and non-switchable discrete (circa-2006) Tesla uarch graphics, to a modern ultrabook or workstation laptop with a Kaby Lake and switchable Optimus graphics (or a reasonably capable iGPU) is like triple the battery life, and unlocks a whole world of applications that simply won't run without DX11 support. And if you want discrete graphics, Pascal alone is pretty much a game-changer.

There is finally a reasonable enough feature-increment to consider an upgrade from the old Sandy Bridge/Nehalem stuff.

You can use ExpressCard to connect an external GPU. https://egpu.io/external-gpu-buyers-guide-2018/#expresscard2...

Even Thunderbolt speeds can bottleneck a GPU. The effects are particularly severe on minimum framerates/frame-times, as opposed to averages.

https://www.pcper.com/reviews/Graphics-Cards/External-Graphi...

That's PCIe 3.0x4 speeds. In comparison, ExpressCard is either PCIe 1.1x1 speed or PCIe 2.0x1 speed. That means they have 1/16th of the throughput on older models, or 1/8th on Sandy Bridge.

It's a cute way to get GSync monitor support in a laptop (this was not included in mobile until Pascal - yet another reason to upgrade), or to sidestep lack of support for DX11/DX12, but the performance is not fantastic (although surely better than a circa-2006 uarch).

Given the size and price of the eGPU solution you are practically better off doing a compact mITX build in something like the Dan SFX-A4 or Silverstone RVZ01. You get desktop GPUs and desktop processors (TDP is still king of performance, and laptop CPUs are very TDP-limited). The only thing you lose is the integrated display, which you can't really use with an eGPU anyway, since sending back a display stream chokes the link for bandwidth even harder (the link I provided is measured by an external display). So yeah, either get a new laptop or get a new (small) desktop, I don't find the eGPU option all that compelling. Nehalem and Sandy Bridge are still tolerable, that doesn't make them ideal.