waaa ... troubleshoot PC !!! i like ~~~
actually IMO bigsink small sink, when the heat flow stabilize,
still you need to think of how fast the heat flow out of your PC
case, not just the CPU part.
as for dead fan. try goto SIM LIM tower, not SIM LIM square. a
normal brushless fan (those normally you see in PCs) at SL tower
cost S$5, in SL square it is S$10+++
sometimes in SL tower if you run through those spare part shops,
you will find a completely working original sink+fan for a cheap
deal (S$5-30).