hmmm
i didn't know that the fan can be set sideways,
it should always be upside down!!!
it is wrong to come to this conclusion based on tkin's system!
hd5800 series are cool and quiet performers
whereas fermi is an overheating overconsuming bunch
(but they perform better )
it has got nothing to do with the form factor of the card!!
Well what he is trying to point out is absolutely right, let me explain the scenario in detail.
Review environment: Open case, the motherboard lies flat on the table(over a soft anti-static plate), the ambient is usually 20-25c(or lower), also the CPU either uses liquid cooling or high performance air cooler(in all reviews you can see this), motherboard is high end sometimes with copper heatpipe based cooling, the SMPS is kept away from the system, all the heat generated by the SMPS never reaches the system.
Typical home user(india): Closed cabby, poor airflow, ambient is 30c+(here it reaches 35-38c in summer), cpu uses stock cooler so heat dumped in cabby, SMPS in system so some heat affect the components, now add to that optical drives and HDDs also generating heat and obstructing airflow you get a pretty hot cabby.
Now, if your card dumps the heat in the cabby it affects all the components along the card(the GPU draws max power among all components), this is what palit or msi GTX460 does, to remove this heat you'll need a bottom mount fan(most high end cases have these) and set it to exhaust, also a side fan near the GPU that draws in fresh air can help a lot.
My cabby is a cheap one, so no bottom fan, side intake helps lower the temps a bit, but a fully internal exhaust GPU will heat up my cabby and the internal components too much(eg MSI cyclone, palit GTX460).
PS: You can get a rough idea from my system because in reviews GTX460 temps are actually in line with HD5850 temperatures, the new GF104 cheap is a lot cooler, yet it heats up like hell due to a faulty bios in my case.