WOW, 4.5ghz 630
Thats incredible!
Its really tricky stabilising my system @ 14x multi, it's a lot easier on it's normal 16x multi since then it's only 263mhz *16. I have to loosen the RAM timings up a lot to get to 4.2 with the 14x multi.
It was completely tested... I used 2 instances of prime 95 for 10 hours, then used the burn-in wizard on sandra and it's completely fine. I'm too scared to go above 4.2 though... Besides, i'd only probably have another 50mhz or so.
I use 3.85 to 4ghz for normal use, and keep the last 200mhz in reserve for if i need to do some video or music encoding.
I know what you mean though, it's one hell of an overclock! But on the other hand, i've seen P4 640s only getting up to 3.6ghz and no further
So i definalty have a lucky chip.