Is the speed os the water passes from the block important?

[keops]

Or is the amount of the water passes through the block important?

[mindwreck]

both i guess. more flow results from having 1/2" instead of 3/8" or 1/4". flow usually goes down with ID.

[creidiki]

Higher speed - more turbulence - better heat transfer.

However, high-flow pumps are generally wasted on watercooling loops, because you need a high head/flow ratio to be effective with the restriction of tubing, rad and blocks.

[Bloody_Sorcerer]

whats important is volume of water. the more water, the more velocity it will create when it enters the block, thus the more turbulence, thus the more water directly exposed to the block for cooling.

[BGP Spook]

I think the point behind moving a higher volume of water or moving water at a higher velocity is to keep the water that is in contact with the heat-transferring surface at as low a temperature as possible.

Only the water molecules immediately touching the heated surface actually receive heat. So it is important to keep the water moving to replace the recently heated molecules with the unheated ones.