In short: I recently replaced an RTX3060 by an RTX3090 in my Core X Chroma. After a while (didn’t start immediately), the Thunderbolt connection started to disconnect periodically. At some point it got so bad, and basic troubleshooting had no effect, that I decided to put the RTX3060 back in for testing. It worked with none of the problems. After I put the RTX3090 back in, I have been unable to have it detected. The card isn’t dead because it WORKS in a desktop system.

I’m really puzzled by this problem, and the combination of factors, also because I was even power-limiting the RTX3090 to 80% most of the time, so it’s not like I was pushing the hardware.  On the one hand, the pattern feels like SOMETHING/component deteriorated over time, but what could make the difference between an RTX3060 and RTX3090 sitting in the enclosure (?). Does that somehow put more load on the laptop in a way that could explain the disconnects?

More details that might be relevant (can give many more if desired...):

• GPU is used for compute, most of the time happens entirely on the GPU, so Thunderbolt traffic shouldn’t actually be all that much apart from when loading models. The disconnects happened at other times
• I checked, and for example the Ethernet connection on the Core X is functioning in the scenario where the RTX3090 is not recognized as eGPU
• 3090 is an INNO 3D iChill, uses 2x 8-PIN connectors, no adapters used or anything. Didn’t do anything special to the GPU apart from experimenting with MSI Afterburner for basic power-limiting
• I do have an HDMI output connected, only because that seemed to be the only way to not LOSE the eGPU frequently (I had to play around with laptop BIOS settings and this particular trick to initially get the 3090 to work… it took some trial & error instead of just replacing the 3060)
• when I put the 3090 in and power up the Core X, the LEDs of the card will light up, but the FANS don’t do anything. The person who afterwards tested the card in his desktop for me, says that the fans DO spin up when he starts his system
• when I connected the CoreX + 3090 to another laptop with thunderbolt, Windows 11 installed Core X drivers, and Device Manager reported an RTX3090 device. I wasn’t able to use it after installing NVIDIA drivers, but that might have other causes.

I’m not sure what’s going on…  Getting the 3060 to work at first was a bit of a bumpy ride in terms of laptop BIOS settings, drivers etc. Then replacing by the 3090 required some additional tweaking. But the developing disconnects and my inability to “find” the 3090 again after numerous different configurations, driver cleanups and reinstalls etc. is a mystery to me. The ONLY thing I can imagine, is that because of all the troubles and troubleshooting, I have frequently disconnected and reconnected the Thunderbolt cable, also while the system was running. But then again, even after all that, the system works with the RTX3060.