Bottleneck calculators are online tools that estimate if a component like the CPU will restrict or "bottleneck" the performance of another component like the GPU. To use one, you enter the specs of your CPU and GPU. Popular calculators are from sites like PC-Builds.com and Pc-Specs.com. For the RX 7900 XT, you generally want a higher-end modern CPU to avoid bottlenecking at higher resolutions like 1440p and 4K. Bottleneck calculators will estimate the percentage of GPU performance you may be leaving untapped with your current CPU. The lower the percentage, the less bottlenecking. Under 10% is ideal, but up to 15% may be acceptable if on a tight budget. Over 20% starts to become more noticeable. For the RX 7900 XT at 1440p, an older quad core CPU may show a 50% bottleneck while a modern 8-core may show only 5%. At 4K resolution, even older CPUs have less of a bottleneck effect since graphics workload is higher. But a newer CPU is still recommended. Use bottleneck calculators as a general guideline. Real-world performance depends on many factors. Test across various games and applications. Pairing the 7900 XT with at least a 6-core/12-thread modern CPU like the Ryzen 5600X or Core i5-12600K is recommended as a starting point.