Hi!
If your ram runs too hot it can affect the reliability of your memory. Some memory has been known to fail if it's too hot!
If you're running BH5 or UTT ram you typically use a lot of volts to ensure stability - 3.2V+ (standard ram is about 2.5/2.6V or so). These modules require active cooling (a fan over them) otherwise they are unstable, are very hot to the touch and fail prematurely
People disagree about the advantages and disadvantages of heat spreaders (which is what I think you're referring to [your link doesn't work!] (
http://www.overclockers.co.uk/acatalog/copy_of_Akasa.html)). Theoretically they should help as they remove the heat from the ram but people sometimes get better clocks without them. Often it depends on the quality of the thermal pads used to attach the heatsinks