This was solved over a decade ago in the enterprise world with an attachable bracket on the end of the card that fits into a slot at a fixed width so it is supported in the vertical axis by both the standard rear case slot and the new support on the forward side.

Nvidia had provisions on their Quadro's to bolt this bracket that all HP Z-machines used and I believe some Dell workstations as well.

The fact that these new cards are even heavier than a K5000 and yet there are not supplied attachment points for such additional support in some way sucks. it comes down to the fact that self-build PC case manufactuers aren't working together and with card suppliers to have a standard- nay, ANY provision for additional support.

Whereas in the enterprise world where the entire system is engineered at an extremely high level with communication from the vendors with the OEM (like a HP Z 800 machine)

That's it. It's not like HP had some magical patent on "hey just have a little extra bit of metal slide into a slot ad a fixed width inline with the PCIe slot". In fact, they made it extra-wide and attached to the hard drive bays in the Z800/820/840s as if they were anticipating modern cards to be bigger than the Keplers/Pascal cards at the time.

---

That said, the level of cracking shown here on the FR4 of these 4090s can only be the result of some pretty significant impact loads. These things were installed unsupported in a case and got dropped off the back of a truck, for sure. Or they were actually pulled out of a dumpster by an employee at a facility that had literally been doing fatigue vibe table tests on machines for an OEM...