Approximator to the rescue!
I've used a MCW5002 as the GPU block. Don't have PQ for TT Bigwater, nor C/W. Anyone?
CPU = 70W and GPU = 30W.
Code:
Layout Pump W Flow Water C CPU C GPU C
Serial Iwaki 30 30.9 9.46 4.9 17 11.18
Serial Iwaki 20 12.8 8.08 4.37 16.6 10.65
Serial D4 11.8 6.6 4.35 16.82 10.71
Serial L30 15.6 5.25 4.58 17.34 11.03
Serial MCP350 5.3 4.31 4.22 17.26 10.76
Parallel Iwaki 30 32.89 15.75 3.65 16.18 9.1
Parallel Iwaki 20 13.5 13.27 2.33 15.09 8.5
Parallel D4 12.38 10.36 2.32 15.43 8.54
Parallel L30 17.22 8.44 2.55 15.99 8.81
Parallel MCP350 5.52 7.17 2.17 15.9 8.49
Now all of this below is plus/minus one trillion degrees because its all interpolated graphs and guesswork and it is combining testing results with different assumptions and bunch of other stuff that has BillA groaning and Les vomitting blood, and ScienceWiz slitting his wrists. Don't care, it gives a good guide as per above.