Again, did you try setting the GPU for Maximum Performance in Nvidia's drivers? Does the speed improve when lowering the IR
@JMC47 - Even if the increased IR adds noticeable stress to a CPU, Wind Waker should not be dropping FPS like that with an i5-2500K OC'ed at his level. I had no trouble doing it myself with inferior hardware. Other games maybe, but WW is super-light. It looks like an under-utilized GPU from what GPU-Z says.
@JMC47 - Even if the increased IR adds noticeable stress to a CPU, Wind Waker should not be dropping FPS like that with an i5-2500K OC'ed at his level. I had no trouble doing it myself with inferior hardware. Other games maybe, but WW is super-light. It looks like an under-utilized GPU from what GPU-Z says.