When it comes to high-performance gaming and content creation, faster RAM can definitely provide benefits. However, the performance differences between the DDR5 speeds you mentioned (5200MHz, 5600MHz, 6000MHz, and 6400MHz) may not be as significant as you might expect. Let's break it down:

1. Gaming Performance: For gaming, the difference between these DDR5 speeds is likely to be relatively small. The GPU (in your case, the powerful RTX 4090) and CPU (Intel Core i9-13900K) play a more significant role in determining gaming performance. While faster RAM can help, the gains are often minimal, typically in the range of a few percentage points.

2. Content Creation and Productivity: In tasks like video editing and rendering, faster RAM can provide a more noticeable performance boost. Applications that handle large datasets or perform memory-intensive operations can benefit from higher memory bandwidth. However, the difference between the mentioned DDR5 speeds may still be relatively minor.

3. Price and Diminishing Returns: As you move up to higher DDR5 speeds, the price premium tends to increase. The performance gains, however, may not scale linearly with the cost. In other words, you might encounter diminishing returns, where the extra cost of the highest-speed RAM may not justify the relatively small performance gains over lower-speed options.

4. Compatibility and Stability: It's important to note that higher-speed RAM kits may require more careful tuning and have a higher potential for compatibility issues. Ensuring stability at high speeds can sometimes require manual tweaking of timings and voltages. Lower-speed kits, on the other hand, tend to be more plug-and-play friendly.

Based on your specific use case and the powerful components you've selected (Core i9-13900K and RTX 4090), I would recommend considering the following:

• If you want the best balance of performance and value, the 5600MHz DDR5 option would be a solid choice. It offers a good speed bump over the base 5200MHz without a significant price premium.
• If you're willing to invest a bit more for potentially better performance in content creation tasks and you're comfortable with the possibility of manual tuning, the 6000MHz option could be worth considering.
• The 6400MHz option, being the highest speed, may offer the best performance in memory-intensive tasks. However, the price premium may be significant, and the real-world gains over 6000MHz might be minimal.

Ultimately, the choice depends on your budget and how much you value the potential performance gains. In most cases, the 5600MHz or 6000MHz options would provide a good balance for your needs. I recommend looking at benchmarks and reviews specific to your desired RAM kits to get a better idea of the performance differences in your specific use case.