Zero to Extreme (My second OC)

Hi everyone. I'd like to ask a question or two, but both come with a bit of information. This one is about OCing and CPU voltage.

I'll start with my OC history. Right now, I am on my first custom built desktop PC. Current build:

Intel i5 750 (Quad Core 2.66GHz stock)
4x1GB OCZ DDR3 PC3-8500
Gigabyte P55M-UD2
Corsair H50 Water Cooler
PALiT Nvidia GeForce 9500GT
OCZ 1000W Silent PSU

I had researched for months on parts and I did some research on OCing. With some step by step YouTube tutorials, I was able to up my processor to 3.5GHz. Currently, I have the system at 3GHz because of random crashes. I suspect the culprit to be a mix of FSB and voltage issues, however I never tweaked the voltage itself due to fear of frying the CPU. The time for proper OCing of this system is passed now, as I'm getting a whole new set-up aside from the PSU as 1000W should still be enough. September build:

Intel i7 Extreme Black 990x (Hexa Core 3.47GHz)
6x4GB Corsair Vengeance DDR3 PC3-12800
Asus Rampage III Extreme Black Limited
Corsair Water Cooler (undetermined model)
MSI Nvidia GTX 590

Now for my question...

...where am I headed to get 4.5GHz with a stable FSB:RAM and voltage?

I'd also like to water cool the GTX but it seems a bit to pricy with all the other parts I'm scraping to get, as well as actually OCing it seems a bit difficult...

Edit:

P.S.

Yes, I read the OC sticky. I'm simply uncertain after my failed i5 OC...