It's fair to say that the one giant Rad is all you really need. those load temps are proof!
This is not really true because I can tell you that these R9 290x heat much more than the HD 7970s.
Before the 290x, I had QuadFire 7970 overclocked 1240/1600 24/7 with the same watercooling setup but without the external radiator and without the external pump. The water temperature during load could jump to 34'C - 36'C and now I never see it exceed 32'C.
You cannot claim the proof you are saying because you are not comparing to anything.
Also, I gave the water and ambient temperature so the people calculate the Delta T. Its the Delta T that is important if you want to confirm if a watercooling setup is good.
Ambient = 25'C and water = 31'C... this mean Delta T = 6'C
Also, I know the external could be enough but it would probably give me a Delta T of 15'C (water at 41'C) and I don't want that.
I also want silence.
Interested in how the first action wasn't a benchmark to make sure performance is where it should be? Your rig has several potential position points of failure.
Can you name them for me please? It would greatly help me.
Because yesterday I was playing Battlefield 4 at 8044x1440 Ultra settings on a 64 players map and I was getting average of 70 fps. (On stock clocks on the cards).
This rig just had the 290x a day ago so I have many tests to come.
( I have a 1 month old new born boy here, time is harder to find)