This is what I did:
I received my RTX 4090 Phantom a few days ago, i checked the adapter and notes it was an Astron adapter. I did a quick botched job installation (octopus style) with the purpose of just checking to see that the GPU boots and runs.
I confirmed the GPU is fine, after which I uninstalled it again waiting on my CableMod cable to arrive, but that is still one to two weeks out from arriving looks like.
One day later, GN posted this video, which I watched with great interest.
After watching the video, I concluded that the chances my adapter would melt would be overwhelmingly low, so I proceeded to do some cable management on the 4 PCI-E 8 pin cables I had installed (only needed 3 though) to tuck them better into the case.
After installing the 4090 into the motherboard, I used 3 screws to screw it in place, and didn't use the VGA holder due to a lack of space (occupied by the PCIe cables tucked in there). Motherboard is reinforced however, it's screwed well enough in it's unlikely it will break anything even in case of an earthquake.
The first issue came with actually connecting the adapter to the 8PIN cables, they requires heavy use of force to connect (the connections click when the cables are NOT fully plugged in, and plugging them all the way in requires a healthy use of force).
The adapter itself doesn't make any clicking sound when plugged into the GPU, so when I saw it plugged in correctly I used force to jam it in even if it wouldn't go further in at a glance (only forward pushing force, no horizontal or vertical). I took around 10 minutes of pushing it in, inspecting the plug on all sides, pushing it more until I was satisfied it was as plugged in as it can be.
I wiggled the adapter plug left and right to see if it would move, it stood in the GPU rock solid and wouldn't flinch to either side. Though I didn't use force here.
The cable is bent around 4cm~ away from the adapter plug, mostly being bent downwards. There is no vertical bending present.
The PC booted fine, installed furmark.
I lowered power limit to 80% and furmark was drawing 350-360W at 100% GPU usage, temps were 60-61 for a 20 minute test (I didn't have time for an 1hr torture test).
During the test I inspected the adapter constantly, since I don't have a FLIR camera I did the old fashioned way, physically gently touching the adapter to notice it's temperature.
Temperature was hot but not burning hot, it was around the temperature of the backplate. I'd say they were both at 55-60C during the test. I could keep my fingers on the adapter without feeling a burn sensation on the skin.
⚠️ Only touch the adapter very gently to get a feel of it's temperature if you do this, don't exercise any force on it ⚠️
I'm currently running optimized efficiency settings (+1500MHz memory, PL 80%, curve optimizer at 2625MHz 0.900)
Furmark is pulling up to 250W with these settings, GPU temperature dropped by 10-13C to 48-50~ and the adapter is also not heating up as much as before.
Prolonged torture tests will have to wait until I have more time for them. In cyberpunk I noticed around 150-180W power draw with RT psycho settings during the benchmark.