https://www.dsogaming.com/articles/heres-what-happened-to-the-12vhpwr-power-cable-of-our-nvidia-rtx-4090-after-two-years-of-continuous-work/
Pic related is what the official connector that came with an RTX 4090 looks like after two years of regular use. Nice melted plastic, and this card draws 150 watts less then 5090. If you own a 5090 and don't undervolt you are at risk of cable failure and fire in the future it's as simple as that.