I see, just wasn't sure if one is more reliable, and I saw one has copper/brass for sure since you can actually see it and the other may just be aluminum so it may pull heat off the gpu better, wish I could see idle and load temps for the two cards >.<
In benchmarks I've seen, rev. 2 (the bottom one) actually runs cooler, and quieter even maybe. They do put air in your case, so if you did get Rev. 2, you need great case airflow. I'm also not sure rev. 2 has voltage control if you're interested in overclocking.