Hello,
This is the first time I'm posting/replying in this forum (although I'm not exactly new), so HI all!
About this setup, I just think the problem as mentioned be4 is the high flowrate trough the radiator.
In the radiator, the longest the water can stay in into it, the more it will be cooled down, BUT it is also true the faster the water can go though the waterblock, the more heat will be dissipated.
I think with other radiator for higher flow, less passes and more tubes, your new pump would outperform your new one, but as it was mentioned be4, you've lost your "sweet point" of your setup. The heat exchange in your waterblock is higher, but your radiator now it's less efficient at this flowrate. Just try to get another one.
Francisco
PD: Sorry for my bad english, but I'm not english
