Consider upgrading your chipset.
Consider upgrading your chipset.
Your setup includes an OPNX motherboard with a dual-core CPU, and you're considering upgrading to a quad-core processor. With a 305-watt PSU, it should be feasible depending on the new processor's power requirements. Just confirm the new CPU's wattage needs and ensure your PSU can handle them.
The motherboard's chipset can handle multiple Core 2 Quad processors. You might need to upgrade your BIOS, but it should function properly. A 305W power supply shouldn't cause issues unless your graphics card is very demanding. The main concern could be your CPU cooler's strength. What temperatures do you typically achieve with your current CPU? If you're on a tighter budget, the Q9400 is a good choice—it costs around $9 on eBay with free shipping, fits your board, and offers more cache than the Q8400.