I am really stuck on this one. I recently got my hands on a second 6870 and I am trying to get it to work with my computer. However as you can guess by the title I get crashes once I get into windows and BIOS reports a hyper transport error. I am no professional when it comes to overclocking and have a very limited understanding of things like busses and northbridges (I am a software dev). I have tried bumping up the voltages of ram and other things in m BIOS but nothing seems to help. The closest I got was bumping my RAM voltage up to 1.59 from 1.5 in which case it lasted about 5 minutes before crashing. I am completely lost as far as what to do and I have read hundreds of threads and tried various suggestions. I did have another graphics card in there once upon a time which was not as powerful and it ran fine.
I should also note that while I have two 6870s one is made by visiontek and the other is xfx. They are not crossfired (I don't even know how to do this yet). Also I had to get two 6pin splitters because my psu only had two
Check your PSU voltages, it can as well be that you are overloading one of the +12 volt rails so swapping connectors might work.
I'm going with bad PSU. That thing is total junk and should be replaced. Little red voltage select switch, ~575W on the 12V rails (it claims) and only two 6pin PCIe plugs. My 500W PSU had two plugs. If it could really do 575 it should have a lot more, or 6+2 plugs.
125W CPU + 2x150W GPUs + 50W for board and stuff = 475W. I'm guessing your PSU can't even really do that. It could also be a HT error, more so if you are doing any OCing. But that PSU needs to go.
voltages are within spec, swapped two connectors and still got a crash
Edit: Guess I will order a new psu, recommendations?