Try to be less rude and less arrogant. You'll get along a lot better with people on this forum if you try harder.
PS. You wasted two years on your engineering degree if you think it is EASIER to cool 200W sandwiched within a 1 inch space (200W per inch) than it is to cool 100W over 1 inch then another 100W over another inch (100W per inch). Yes, you can do it. But it's not going to be as easy and it will be noisier.
Wrong. Look at reviews, both cores on the GX2 run cooler than the second GPU in any X2. That is the fact, no need for expeculation. The reason I gave is why that occurs. I know the basis of termodynamics, thanks and btw it's all about VOLUMES of air that will have contact with the chip/fins and SURFACES (of the chips and cooler fins in this case) not about the space between the pcbs, 1 inch or whatever. As long as you move enough air, and the GX2 does, it doesn't matter how much space you have. The ammount of air that is moved into a case is much higher, there's mor free space, and the fans move a hell of a lot more air than GPU or CPU coolers, but those cool much better. Tell me by your theories why... I'll tell you the overall VOLUME of air is bigger, but the VOLUME of air that makes contact with the SURFACES of the cooler are the "same" (relative to speed) in both cases, but case fans can't provide the chips with cool and clean air. Also as important is HOW that volume of air gets to the chip or the fins. Clean straight air cools a lot better. In the X2 the second GPU does not get clean straight air. Next time check your facts before calling me.
EDIT: I forgot to mention the most important one: the temperature of the air. It doesn't work exactly as in the example I'm going to give but similarly and you can get the idea. If with no air circulation a chip was 100 C and our air temperature is 20 C, over the time and with perfect heat tranfer both will eventually end at 60 C, on the contrary if our air is already at 60 C the next chip will only get to 80 C. As I said it doesn't work that way, so linearly and without taking into account volumes, densities, thermal properties, etc. The same effect does occur though. With moving air is the same, but quicker.
PD. Now, when you SLI two of them, in most mobos the upper one will be almost unable to get fresh air because the other one is in the way and the second one is usually below the path that the air takes inside most cases, so the very first need I mentioned, fresh clean air delivery is destroyed and the cards can get hot hot too.
EDIT2: There's yet another factor to take into account, and that is that the contact surface of the chip is also important. Trying to cool down 200w through a contact surface of 256mm^2 is much harder than doing it on a 480mm^2 one. And that's one of the reasons the GTX295 WILL be cooler (speculating, but I'm going to enjoy saying "I told you").
100% Effectiveness in my assumptions. As I speculated (based on facts and precedents):