Hello! For a budget of 20-25k, you can still build a decent PC that can handle gaming and academic simulations. Here's a suggested build for you:
Processor: AMD Ryzen 3 3200G - This APU comes with integrated Radeon Vega graphics, which will be sufficient for light gaming and academic simulations.
Motherboard: ASRock B450M-HDV R4.0 - A budget-friendly motherboard that supports the Ryzen 3 3200G and has room for future upgrades.
RAM: Corsair Vengeance LPX 8GB DDR4 3000MHz - A single stick of 8GB RAM should be enough for your needs, and you can add more later for better performance.
Storage: Kingston A2000 240GB NVMe SSD - A fast SSD for your operating system and frequently used programs.
Power Supply: EVGA 500 W1, 80+ WHITE 500W - A reliable power supply from a reputable brand to power your components.
Case: Tecware Forge M - A budget-friendly case with good airflow and cable management options.
This build should be able to handle games at lower settings and run academic simulations smoothly. However, keep in mind that this build is on the lower end of the performance spectrum, so you may need to adjust your expectations accordingly. If you can stretch your budget a bit, consider upgrading the CPU to a Ryzen 5 or investing in a dedicated GPU for better gaming performance.