Can anybody tell me what the issue is with that, I switched the cards and it doesn't matter, the card in PCIe x16 slot 1 gets hotter than the card in PCIe x16 slot 2.
How is that possible? I have CrossfireX birdge installed but CrossfireX is not enabled in Windows 7.
I have a Gigabyte X58A-OC mb with XFX HD6870 dualfan cards.
Is there something i'm doing wrong or is this normal?
It seems like the most likely cause of this temperature difference is the location of the slot. I am assuming that since you seem to be using this mining computer as a desktop, it is in an vertical case (typical). You are saying that PCIe x16 slot #1 is hotter, which is most likely above PCIe #2 on the motherboard which makes it vertically above PCIe slot #2 (correct?).
Now in terms of airflow: The bottom video card
would be taking the cooler air that is likely at the bottom of the case, drawing it in through the fan(s), and then spitting it back out between the fins of the heat sink. The top video card
will take in the air that is directly beneath the fan(s) and doing the same thing. However, much of this air that the top card takes in has already been heated by the bottom card.
This is my guess, and I believe that it is quite common. I would look into directly controlling the fan speeds (fan speed of the top card would be significantly higher). Or you can switch to a typical mining rig setup where you lay the mining rig down without a case (mobo is parallel to the ground). This allows some hot air to exit upwards without the case stopping it (note that the "top" card will still run a little hotter).
Hope this helps.