If you went with 2 radiators would you need two loops? or both in one loop?
depends what you want, you could do.
I have had two rads in one loop for two years now.
as long as you have a good pump then there is no reason why not
I will be planning on OC-ing and going to TRI SLI 580
tri SLI 580s would be fine on a quad.
they would probably be alright on a triple tbh
remember that GPUs are less sensitive to heat.
it depends entirely on how much oc headroom you want and if your cards genuinely benefit from lower running temperatures.
when I had my 480s it was just nice to have them quiet but i found that the lower running temps allowed for massive overclocking potential.
two quads for trisli sounds like misinformation to be perfectly frank.
So if you have 2 GPU's in cross fire and a CPU (for this argument socket 2011 and 7900 series) (all overclocked) a 480 (120.4) should be sufficient?
Does that mean a 560 (140.4) will show diminishing returns?
relatively speaking yes.
with the right fans and case it should be fine. 2011 runs about the same temp as a 1366 cpu
7970s are fairly cool running cards and should only generate heat when they are heavily clocked.
it all depends what you want to cool.
a pair of 480s would heat up a loop loads more than a pair of 6970s for example.
there is no hard and fast rule, just guidelines.
for example. if you look at my tj07 build log in my sig, I have a 480 and a 240 rad.
these were originally cooling a gulftown cpu, 4890cf and a motherboard.
all with massive clocks on
the rad setup was about right, I could have gotten away with a 120 instead of the 240 but I wanted to fill the space in my case tbh.
I now run the same watercooling hardware but on a cpu and gpu block.
the cpu and gpu I have now run loads cooler and there is no mb in the loop so it is total overkill.
if I removed the 240, I doubt I would see a temperature change.