-Make the water block bigger than the peltier surface to maximize the time the water is in contact with cold metal and maximize the internal surface area of the water block
-Install swirl inserts in the feed pipe to maximize turbulent flow
-Mill the block itself down so that it is as thin as possible (shortening the time it takes for the entire block to cool and minimizing energy wasted cooling copper)
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If you want to have a thin base plate with a surface area that extends pass the pelt it wont work. Basically you don't allow enough time for the coldside of pelt to spread cooling throughout the baseplate.
A very detail explanation why.
http://forums.procooling.com/vbb/sho...73&postcount=4
http://www.overclockers.com/articles305/
If the liquid is also cooled, then the water block's temp is ..whatever.. and a thinner 1/8" spacer is perfectly acceptable.
WB pattern that will also perform well.
http://forums.procooling.com/vbb/att...3&d=1093346558