Second 3090 or get 4090 instead?

I just want my models to train faster

Ryzen 9 7900X

64GB DDR5

Edit:

Sorry!! I mean for a new system, buying a used 3090 for $700-$800, having *just* bought one for $700. I would be selling the 3090 I just got hoping to get $800 for it and putting that money towards a 4090.

So in total I have spent $700, and getting another 3090 would put me at $1500. A 4090 would be $200-$400 more but would be …

ddr5 deeplearning edit faster mean money ryzen selling train