Should I build a new gaming PC or upgrade my current one with a S$4,000 budget?

You can afford a high-end build, but you don’t have to spend every dollar. Something around the equivalent of US$2,400–$2,500 could already give you an excellent 1440p gaming PC, including a fast X3D CPU, 32GB of RAM, a 16GB graphics card, a 2TB SSD, and a good monitor. Save the rest for peripherals, future upgrades, or just keep it in reserve.

With that budget, I’d build a completely new system rather than upgrade the old one. The graphics card, memory, storage, power supply, and probably the platform would all need replacing, so there isn’t much worth carrying over. A modern gaming build with a Ryzen 7 X3D processor, 32GB of DDR5-6000 memory, a current-generation graphics card, a 2TB NVMe SSD, and a quality 850W power supply would be a strong choice.

A staged upgrade is possible, but it only makes sense if you’re trying to spread out the cost. An SSD would improve general responsiveness, but the old graphics card and 4GB of RAM are major limitations. Once you replace the CPU, motherboard, memory, graphics card, and power supply, you’ve effectively built a new computer anyway, so I’d replace the system in one go.

Don’t overspend on parts you won’t benefit from. A sensible build with a modern gaming CPU, 32GB of DDR5, a good 1440p graphics card, fast storage, and a reliable power supply should be more than enough. The absolute top-end options may fit your budget, but they aren’t necessary unless you specifically want 4K gaming, very high refresh rates, or heavy productivity performance.