I've never really been sold on the whole external GPU thing, but I can't deny this Thunderbolt 5 eGP

The whole external graphics card thing is one of those technologies that sounds super appealing, but tends to fall down on practicalities like price and performance. But I gotta admit, this new Kickstarter-funded eGPU dock based on Thunderbolt 5 is incredibly slick and has enough features that you could almost view the eGPU bit as an extra.

, as it is known, claims to be the world's first eGPU dock with Thunderbolt 5 support. That's critical, because Thunderbolt 5 offers 80 Gbps bi-directional bandwidth plus a 120 Gbps one-way "Boost" mode, the latter being designed to support multiple really high-res and high-refresh displays.

So, the first question is, will Thunderbolt 5 and 80 Gbps of bi-directional bandwidth be enough to keep a modern GPU fed? After all, if it is, you could then turn any laptop with a Thunderbolt 5 port into a gaming machine. Er, right?

That's actually a tricky question. The problem with eGPUs isn't just pure bandwidth; it's latency, too. The Humbird 3 has a full PCIe x16 slot for graphics cards, but it can't do the full x16 bandwidth by PCIe Gen 4 standards, let alone Gen 5.

The 80 Gbps of Thunderbolt 5 basically means you're looking at a PCIe x4 data link, which requires 64 Gbps. Now, in theory, it could be possible to use the Thunderbolt 5 "boost" mode to feed 120 Gbps upstream to the GPU, but I don't think that's happening here.

To the best of my knowledge, PCIe doesn't support that kind of asymmetric setup. Indeed, the Humbird 3 Kickstarter page says the GPU slot is Gen 4 x4, so that's that, really.

Of course, whatever the bandwidth, latency is also an issue. There's always going to be a bit more of that with a GPU sitting in an external dock running over [[link]] Thunderbolt 5 compared to a GPU hooked up directly via PCI Express.

We haven't done any Thunderbolt 5 eGPU testing yet, but with an plugged into an Strix 18 laptop that has Thunderbolt 5 and its own RTX 5090 mobile chip.

Long story short, the [[link]] results are very mixed. The RTX 5090 desktop hooked up to the Strix nearly doubles frame rates in Cyberpunk 2077 at native 4K. But in other titles like Horizon Zero Dawn and Borderlands 4, the desktop 5090 is little or no faster than the laptop's built-in RTX 5090. And don't forget, the laptop 5090 is really a downclocked desktop GPU. So the desktop RTX 5090 has over double the raw GPU power.

Anyway, that all gels with our findings last year. Long story short, even with Thunderbolt 5, the implication is that the eGPU thing still isn't performing anything like a desktop graphics card, not consistently, at least.

As for the rest of the Humbird 3's features, well, you get three Thunderbolt 5 ports, two USB-A, an SD slot, 5 Gbps ethernet and DisplayPort. There's also an internal M.2 SSD slot, a small LCD screen that tells you things like the power draw of the eGPU and data speeds of the various ports, active cooling and even a wireless charging pad for your phone. Nice.

Last but far from least, it has an optional 500W power supply upgrade (for an extra $129), which covers everything up to and including an RTX 5080.

Price-wise, we're currently talking $316 with a claimed November delivery date. The Kickstarter page says the Humbird 3 can be shipped anywhere in the world. [[link]] I'm still not totally convinced by the whole eGPU idea. But the Humbird 3 looks pretty darn useful in plenty of other ways, so it's tempting all the same.

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