A friend of mine struggled a lot with the stock cables on his seasonic platinum, their cables dont work right over 300w on a 2080ti.
If your card doesnt go over 300w after OC'ing you are fine. Otherwise, I'd look into a different PSU or add a proper PSU cable.
For referance, SeaSonic Prime Platinum power supplies come with 6pin to 6+2 PCI-E cables that caused issues for my friend. He replaced his cables with 8pin to 6+2pcie cables and then it worked just fine, but its something worth keeping in mind.
Cablemod kits should make it work perfectly.
That's an odd issue... i wonder why Nvidia cards have a problem? I've used multiple versions of those PSU's (including the old version with the chokes) with 500+watt load Vega 64's attached with no hickups.