No question.
No question.
When you can't spend on a current computer, the Intel Q9550 CPU is still the top choice for that motherboard.
High FSB plays a significant role in performance for socket 775. With DDR2-800 it's best to keep it at 400 and only tweak the multiplier if needed. Otherwise, the FSB could become a bottleneck. For those Pentium Dual-Cores, I recommend starting at 1.5v Vcore and testing multipliers of 9, 9.5, and 10. Since you already have these options, it's worth exploring their potential. A Core 2 Quad would likely offer the best Windows performance for everyday use, though even heavily overclocked units might not surpass a modern 15 watt Pentium Gold dual-core—considering how far we've come in just ten years. PCSX2 works on current systems but may favor clock speed over efficiency, and the Pentium Gold runs at only 2.3GHz.
I believe the chip isn't functioning well. I have a Pentium E5700 and a core 2 duo E7400. With the E5700 I achieved 3.9Ghz once, but it's no longer working. However, at 3.75Ghz it remains stable and reaches 180cb+ in Cinebench R15. That's a 25% overclock without changing the voltage. I'm currently using the core 2 duo in my PC, which runs at 3.5Ghz stably. It doesn't go higher, but it performs similarly in Cinebench. Mostly due to the additional 1Mb cache.