Nothing per se mate, was just the worst of the 4090s I tried. Does not mean it was bad tbf, just had the worse temps, saggiest cooler, worst looking RGB and most importantly, the unusable RGB software for me when I had it. Tried clean Win 10/11 OS installs and it wouldn't work on either, plus it was stuck at 450W although the latter would have been changeable via a BIOS update which I was not aware of at the time. It only came with a 3x8pin too and the adapter mine had didn't click in properly. No issues with it burning up though luckily.
That's really odd because mine came with a 4x8pin. I turn RGB off so not a factor for me personally.
I'm still not sure if I'll keep it due to the whine but then it seems so common it will probably be a futile exercise trying to find one without. I also got it for a 'decent' price so a bit reluctant to return on that basis too.