[Joe]

Been there done that.

Direct core cooling in inefficent. I dont have time to get into it thismorning but heres the basics:

1. there is a significant loss in surface area to cool, you just have the few cm^2 of area to transfer heat to the coolant.

This is EXACTLY the same as running the core in open air with no HSF.. you CAN cool it but you will need an insanely high flow rate of coolant or air to cool it as efficently as with a waterblock.

A Cu block acts as a heat spreader as its much more efficient at conducting heat then water of mineral oil. This allows the Cu block to contact more coolant per second, at more reasonable flow rates, and in turn cool better.

2. the leak risk on direct core cooling after a few power cycles are very real. it can be done, but I do feel more confident having a Cu block soldered together Vs. plastic gooped onto my core.