Ah yes, of course, a mistake in my reading earlier. I agree some cooling for other IC's, particularly those handling the northbridge and southbridge which will be under increased strain on an overclocked system. I see what you mean.
I have a better PSU for the task as well, I will probably pick up an extension cable and do the necessary modifications to it when I visit the supplier next. Not too difficult to do.
I have a slight fear that I may need to use an extra power supply to provide the extra kick required to start it. I have another PSU here suitable for the task but intended to keep it as a last resort. It's becoming more and more clear i'll have to use it though.