Intel Overclocking is done by increasing the front side bus speed (FSB). When you overclock the FSB, the RAM speed increases proportionately........ you get so far and the RAM will not work anymore or become highly unstable resulting in system crashes. The RAM can also be damaged by overheating.

The PC may fail to boot after an overclock for at least one of the following three reasons.

1. the ram can't cope
2. the CPU cant cope
3. the OP sys doesn't like it.

If the PC fails to boot after increasing the FSB speed, you may have to reset CMOS using a mainboard jumper cap as outlined in your manual. So, it's best to familiarise yourself completely with your BIOS setup before starting, so you can restore it to its current settings.

Let's say, (as I don't know enough about your system), that your FSB is clocked normally at 800mhz, and your RAM is running at the normal 400mhz speed for your mainboard.

If you bump the FSB speed up to 1000mhz (a 20% increase) then the RAM speed will now be proportionately increased up to 500mhz, which matches your RAM's theoretical maximum speed.

If your RAM was already running at 500mhz, (doubtful), then you would be prudent to de-clock the ram prior to overclocking the FSB, so that when the FSB reaches 1000mhz, your ram is running at its rated 500mhz.

CPU temperature should be carefully monitored after an increase in FSB speed, also and not so easily done, the mainboard's general temperature should be watched, as it may be damaged as well. The Northbridge chip may require extra cooling in severe cases.

Accurate CPU temperature monitoring is essential, and before and after readings need to be compared, at idle and max load as well, taking care to make accurate tests and comparisons.

Sound understanding of the overclocking principle, Simple mathematics and familiarity with bios settings are all you need.

Always understand there is a risk involved that you could damage your hardware in the process of overclocking, and be prepared to shell out some cash if the worst happens.

You need to switch off TURBO and go to the manual settings, this should enable other settings including your RAM timings.

RAM timings are usually set by the bios and SPD module on the RAM chips themselves when SPD is enabled by bios setting. Disabling SPD should allow manual timing settings.

Fooling around with RAM timings will probably cause boot freezes and CMOS resets until you find the ideal settings. You can check the effect of your timing settings by using the system bandwidth benchmarks in SiSoftSandra, AIDA32 or Everest software. Everest is small and fine and free and as good as the others. (also free).

Generally, the lower the ram timings, the faster the system, but when the system is pushed hard, overclocked etc. ...... the timings may need to be slackened off for stability or even to boot at all.

There are many combinations of ram timings possible, using the benchmarks will help you optimise them.

Will have another look at my BIOS

I have the facility (daft as it sounds), to place my PC in an air conditioned case.  Means I can keep the ambient temps waaaaaaaaaaaaaaay down

Makes a massive difference to MB temps, though strangley, not much help for CPU temps.

It also keeps the air dry.  Always a help