My 5850 has died recently... It was always been really unstable and crashy lately then just finally died a couple of days ago. I took it apart when i was replacing the fan and found that there is a broken ferrite choke I'm not sure if its causing the issues or not but im not gonna go through the effort and repair it if you have any questions just ask in the thread or pm me here are hte pics of the broken ferrite choke and the ebay listing. I will sell this off of ebay to avoid fees. It doesn't post.
Also the only rep I really have is my ancient custom made mining cases thread I made forever ago you can also search my name in search bar you'll see lots of things I have done in the past have not been on these forums in ages.https://bitcointalk.org/index.php?topic=29360.0
Ebay Link: http://www.ebay.com/itm/ATI-Radeon-HD-5850-For-PARTS-/170883474274?pt=PCC_Video_TV_Cards&hash=item27c972e362
Here are the pics :