Pump pulling from CPU does it make a difference?

[nikhsub1]

It will have the exact same pressure drop no matter where it is in a loop.

If a pump produces 100 units of pressure (at the flowrate of the given loop), the rad has a pressure drop (at this flowrate) of 20 units, the res has a pressure drop of 5, and the CPU block a pressure drop of 75, it will be 75 no matter where it is in the loop. X units of pressure will exist at the intake and there will be X-75 units immediately after the block.

Doesn't matter if the order is 75-20-5, 20-75-5, 5-20-75, or whatever. The pressure drop of any given component is a given curve like these:
That curve doesn't change depending on where it is in a loop. Therefore, the pressure drop doesn't change depending on where it is in a loop, therefore the flow doesn't change, therefore the performance doesn't change.

Pressure throughout a loop DOES vary depending on the position in the loop. Remember, pressure is a cumulative beast and each component will have a different PD depending on flow and where it is in the loop. Your above statement is over simplified and not correct. Pressure drop will be different with different amounts of pumping power. The more pump, the more PD we experience. When you think of components in a loop and pressure drop you have to look at the loop as having an absolute beginning and end. The beginning and the end are at the pump outlet (beginning) and the pump intake (end). In your example of 75-20-5 and 20-75-5 etc it is wrong to think that no matter the loop order that each component will RECEIVE the same pressure as it would elsewhere in the loop. It does not work that way. The way to look at your example is in percentages and NOT absolutes as you have presented them. If the WB is right after the pump, it will take 75% of the pressure of the pump. This leaves 25% left for the rest of the loop. If the RAD were to be first as in your example, it would take 25% of the total pressure and leave 75% of it to the rest of the loop, so if the CPU block were next, it would only get 75% of the pressure...

A component's (block or radiator) thermal performance directly relates to flow and flow alone.

Yes, but flow is relational to pressure squared.

But the pressure drop of a component is constant no matter where it is in a loop (so long as the other components do not change).

This is where you must change your thinking.

Flow rate is constant, pressure is not.

Correct.