XFX HD7850 (FX-785A-ZDF4)

Seller Note “It has served me well in a non-gaming PC, but I recently upgraded the drivers and shortly afterwards I started to get flashes of grey specifically when using Google Maps (Aggressive Panning and Zooming). I have run a benchmark for hours on end and don’t see any problems, but there are few apps trigger this issue, so it makes me think this is software rather than hardware. I didn’t have time to debug this, and since I use this in a “business” PC, I have changed to a lower spec graphics card to fix my problems.. I figure that someone with more time might have chance to look at it.”


  • Resistances seem ok, so on to testing.
  • Condition seems a bit rough, HDMI port is very loose.
  • BIOS screen seems fine. Boots into windows, then, perhaps as the card warms up, the entire screen turns to patterned lines, not really like the typical memory issue caused artifacting I am used to.
  • On attempting to load GPU-Z the screen goes blank and stays blank.
  • The sellers note appears to be to be hugely underplaying the issues – not really working with an occasional issues.
  • Need to take it apart and do more testing. Tried the DVI port, but the issue seems the same.
  • Will also check if the drivers are loaded and if windows is reporting any fault.
  • Will crash windows if used as a secondary card.

Update – Reflow of all memory chips appears successful

I suspected a Vram issue, previous artefacts and a crash on driver load. Without an easy way to narrow down the specific chips (suspect it’s one or more of the chips that run along the top of the card under the heat pipe), I decided to reflow all 8 chips. It appears successful, Kombuster is passable and heaven runs quite well. There are remaining issues though, as the HDMI port is very loose and can lose signal if nudged. Also, the thermals of the card seem questionable under load. More to do before it could be sold as working, but progress!