PC Doesn't Boot After Too Much Overclocking

I love games, but what i mostly love about them is their beauty, the graphics and that realistic crap, But if i Play games like Skyrim or L.A. Noire, i get Lag, (Only on Highest Settings)

Heres some of my specs:

Dual GeForce GTS 450s I also have SLI for the 2 cards (are there very expensive SLI bridges that can boost my performance?) 16GBs of Ram (4x8gb) Asus Rampage IV Extreme Motherboard Intel i7 CPU 3.6GHz And 2 Shitty Hard Drives (1 around 350gb and 2nd around 120gb) I have about a 900Watt powersupply that handles crap fine, The Hard drives are both old and slow, im not sure if they are bringing my performance down

So one day, i decided to do some overclocking, i started up the BIOS and i overclocked shit to the max, but then i clicked save and exit and my PC was basicly like this:

I push power button: PC turns on for 20 secs, then turns off i wait about 4 secs and PC starts again, i wait another 15-20 secs and PC turns off again, i wait and nothing happens, The if i push power button again it all repeats,

Basicly after Overclocking my PC doesn't Start, My problem isn't the PC not starting because i can fix that with a awesome reset button on my motherboard,

What i want is to be able to do Overclocking without having my PC restart itself and not manage to stay on for half a minute

NOTE: I reset my motherboard and went into BIOS again, and i had everything on default which works fine, and then i set a few things higher, nothing much, just things that would add a very small amount to my FPS, but still the PC decides not to work!

NOTE: I still had this problem back when i had a single graphics card and about 4gbs of ram,