Most cracking is caused by 'user error', AKA tightening the barbs with a 12inch adjustable spanner. seriously if you overtighten the barbs OR the top mounting Allen bolts it WILL crack. tighten the top enought to compress the O~Ring and you'll be OK. Tighten the barbs hand tight then 1/2turn more with spanner
while useing silicon sealant on the threads instead of PTF tape, and ditto. you can use PTF tape , I do, you just have to be carefull how much you tighten it past 'hand tight' (I do
up to 1 whole turn because it needs compressing slightly to work...
All that stuff about the extra copper saving you in a melt down is tosh, my lexan top went through a 'no pump' episode and what saved me was having the radiator ABOVE the level of the block soby allowing natural convection to cool the CPU...
If it can't convect, the 'heat storage' properties of a few ounzes of Cu ain't gonna help you

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