When assembling a PC, shoving high-end hardware into a case without considering airflow is a recipe for thermal throttling. The key to a healthy system is understanding static pressure.
Positive Pressure
Positive pressure occurs when you have more air coming into the case than exhausting out (e.g., three intake fans on the front, one exhaust fan on the back).
This setup forces air out of every small crack and crevice in the case. The massive advantage here is dust prevention. Because air is constantly being pushed out of the unfiltered gaps, dust can only enter through your front intake fans (which should have a dust filter). This keeps your PC incredibly clean over time.
Negative Pressure
Negative pressure occurs when you have more air exhausting out than coming in (e.g., three exhaust fans, one intake fan).
While this can sometimes result in slightly better raw cooling performance (because hot air is aggressively removed), it turns your PC case into a vacuum. Air will be sucked in through every unfiltered gap in the chassis, bringing dust directly into your motherboard and GPU heatsink.
The Verdict: Always aim for slightly positive pressure. A standard setup of three 120mm front intake fans and one 120mm rear exhaust fan is the gold standard for a reason.