With the TES 1326 Infrared Thermometer literally in hand we found ourselves getting real-world temperatures from the products we test at load (3D clock speeds).
There are two places we pull temperature from - the back of the card directly behind the core and if the card is dual slot and has an exhaust point we also pull a temperate from there, as seen in the picture.
The top card starts to run significantly warmer due to the restriction of airflow when compared to the same card when running by itself. Due to the cards being so close together, we weren't able to pull a temperature from the second card. It did seem to feel like it was running cooler, though, which was probably due to the fact the fan had no issue getting cool air in.
Pulling out the TES 1350A Sound Level Meter we find ourselves quickly yelling into the top of it to see how loud we can be.
After five minutes of that we get a bit more serious and place the device two CM away from the fan on the card to find the maximum noise level of the card when idle (2D mode) and in load (3D mode).
So you've got the two cards in and you're sitting in Windows; nothing has changed with the noise levels which is nice.