Overclocking not working :(

[PsychoticShaggy]

Hi, I'm trying to overclock my CPU (Intel E4500 - 2.2ghz)
Yesterday I managed to change the frequency from 200 to 250. I tried to push it a little further, so went to 270.
When exiting the bios and starting to load up windows I got an error "Overcloking failed, Press F1 to enter settings or F2 to load defults".
I went back in to the bios and changed everything back to default settings and tried again, but still the same.
Now I can only get it to 215, if i try to go any more than that it doesnt even start, just sits in a continuous loop with the fans starting up for a few seconds then turning off again. To stop this I have to disconnect the main power for a few seconds. Then when I reconnect the power and start up it displays the overclocking failed message again.
Please help, this is so frustrating.

Specs are:
Asus P5B-VM motherboard
Intel Core 2 Duo E4500 2.2ghz processor
4 x 1gb OCZ PC2-6400 DDR2 RAM.

Hopefully these will help

 

[PsychoticShaggy]

I have tried changing the DRAM frequency to DDR2 - 800mhz, but that still doesn't work

 

[PsychoticShaggy]

OKay, so I set the DRAM to 667mhz and up'd the CPU frequency to 220, that worked!!!
I tried to up the CPU frequency more but that failed I cant even get the CPU frequency to 225.
I have tried to drop the DRAM down to 533mhz, but that didn't help either.

When it's failing, it turns off from exiting and saving in the BIOS, powers down, then powers up, fans start, HD spins up, then powers down again. Does this continually.