did you use a GPU drive cleaner befor install new card Note: back-up your data on the OS drive before using.
Win 11 24H2 have installed KB5058499
I'm with Trotty on power connections check them very good for seen melted molex connectors from poor contact of connection end making heat when under load.
First of all, you should make sure that your PSU can power the new GPU. When buying the adapter, you should always buy a good quality one. The good quality ones usually have 18 AWG, UL 1007 insulated wires. You can recognize them by the markings on the wires itself. Avoid adapters with blank wires since they are very cheaply made with very thin wires that are not capable of transferring so much current and they can easily melt. Good quality adapters are rated for max 120 W and this rating should not be exceeded. You could probably go a little bit over but at your own risk. If the cables are getting hot (so hot that you can not hold the wires with your fingers and you start to smell burning plastic) during the full load you should replace your PSU. If the wires are getting warm only, that should be fine since insulation is rated for 80 degrees Celsius. Do not bundle adapter cables, instead try to spread them away from each other for improved cooling, and in case of melting and failure of one or more cables, they would not touch and cause a short circuit. Also MOLEX end of the adapter should be inserted correctly in the female end. MOLEX ends should slide easily, which means that all MOLEX pins are inserted into collars correctly. If they are not aligned correctly with collars, they can be pushed back from their mounts making bad contact. After connecting MOLEX always push in individual wires to make sure that they are inserted all the way in. And that should be it, note if can pull wire out of its place means the lock isn't working and needs to be re-arched to make connection with lock.
As you see the melted pins were not fully incerted. good practice to push all connectors (metal) after mating the plug for the cheap vendors build crap wires.
Note: with no power to PSU