yes - i have an old waterblock thats too big for my new motherboard --
Hose clamps is probably the right word for it
Could you post pics of your stuff? Be nice if you had the names for your parts and the terminoligy down.
Like what brand the block is, what pump brand and radiator brand etc. What CPU your going to cool etc. I'm worried you might have a prebuilt kit like Koolance, Thermaltake, etc etc.
If that's the case, then Rubix might be right.
I'm leary of recommending much until I know LOTS more info.