I never said an AX450-PN wouldn't run it. But this was not a "what supply should I buy" thread, but rather a pointed question regarding the SP2-450's characteristics.
But if you desire to debate the relative merits of the two, bear in mind that a P4-630 at 4GHz draws roughly twice the power than does an A64 3000+ at any possible clock. AMD cpus have an enormous advantage in terms of power consumption and heat production, so it is when you try a particular supply on an Intel rig that you really learn about its 12V capacity. By that measure, the SP2-450 is rather impressive in my experience and that is the answer I will give regardless of how impressed I (or others) may be with the FSP alternatives.
I like FSP a lot, but I really feel the AX500-A (actually 460W rated) is more the natural competitor for the SP2-450, making the SP2 somewhat of a bargain. Throw in the fact that you get one for 99 bones in the very spiffy SonataII case, and you have far and away the least expensive case/PS that a self-respecting OCer is going to aspire to. The AX450 brings substantially varying sustained and "peak" 12V power figures that hint at a lesser actual capacity and load-driving ability than the SP2-450 or AX500-A. In the end if you pay attention to one number alone, let it be the price. When FSP charges 80+ bucks for the AX500-A and rates it at 460W you have to suspect there are real limitations to the unit they will sell you for $49, regardless the other numbers associated with the device.