Single BIP or BIX enough to cool 2 video cards?

I'm wondering is a single BIP or BIX enough to cool 2 6800GTs? There will be no CPU in the loop, just 2 video cards. I'm only thinking about a single rad because I read that GPU's are slightly easier to cool than a CPU. Thanks.

They are effiecient enough to cool both cards without too much effort. Even with a slow/low noise fan they will be up to the job.

I want to clarify that this set up is either BIPI or BIXI not aBIPII/BIXII/BIPIII/BIXIII.

well the BIX I is rated about 3134BTU per hour (watts * 3.38 = btu/h) whatever the wattage rating of the vid card (x2) i will assume that the 6800gt is horribly inefficient (which its not) and its a way high wattage gpu (which its not) SO!

say there like 50w each (way overestimating them)

50 * 2 = 100w * 3.38 = 338 Btu/h output

assume the blocks have a 65% efficiency of heat transfer (which I would hope they have a higher heat transfer than that!!) and add in the heat of the pump which I would guess is maybe like 75BTU/h

so 1/.65 * 338 = 517BTU/h + 75BTU for the pump = ~600 BTU/H and due to pumping losses and the inefficency of the radiator, you should still have lots of headroom.

If I did something wrong with the math here someone please tell me ( i think I did something wrong) but the sumbers should be relatively close.

Well I didn't really check over your math, but you don't really need to account for the inefficiency of the rad. The rating given is its efficiency, however that's with 100cfm fan on it, so the only time you would reduce that is when you would be sending less air than that...which you would most likely do because a 100cfm fan is intolerably loud.