Don't upgrade to DDR5 for your RTX 4090 at 1440p.

No.

Your RTX 4090 is already bored at 1440p. You’re CPU-bound in most games, not RAM-bound. Upgrading from DDR4-3200 to DDR5-6000 might net you 3–5% in a handful of CPU-heavy titles, but that’s the best case. Usually it’s within the margin of error.

The real cost is the new motherboard and RAM. You’re spending $300+ for frames you won’t feel. That money is better spent on a 4K monitor, a faster CPU down the road, or literally anything else.

This is not where you find your missing performance.