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Sapphire HD4850 Red Light District


Well-known member
Jan 26, 2009
Okay, so the Red LED's fire and video disappears, and sometimes locks up.
Possible problems are power or temp, right. Wrong/Maybe.

Googling brought up lots of Info on possible causes but none seemed to fit this situation.

Added P55A-G55 to the GPU search and bingo, got an exact match to this system, minus psu, but no solution.

The psu is a TR2 RX 650. Impressive name. One of those refurbished ones that I picked up on a NCIX sale,for squat. I did have power issue with one of the 6-pin pci-e connectors dis-functioning the card when it was on the GA-P35-DS3R but swapping to another connector fixed this situation.

Note: I won't buy another Thermaltake PSU again.

So swapping connectors didn't solve this problem this time, so I knew that the problem was a dieing psu, faulty motherboard, or just plain crappy BIOS.

I found no solution to this situation, and was just about to replace the HD4850 with Crossfired HD3850's, when that silly blue LED's flashing caught my eye. That LED is used as a visual clue as to what stage the
APS (Active Phase Switching) controller IC on the MB is operating at.

As I said, a possible BIOS problem, so I went into the BIOS to attack all the Power Saving Settings, for which there really aren't any. Cheap BIOS as far as I am concerned. The only settings that I could find that allow me to adjust any Power Settings was for the APS, with 2 settings, Auto or Disabled, and it was on Auto, so Disabled is the next choice.

Well it's been 3 days now and not a sign of any problems, even BF3, BFBC2, Medal of Honor or COD4 has not caused this system to even hickup.

Problem solved. Hopefully this thread will show up when someone googles Sapphire HD4850 Red-Light issues, and it saves them a lot of headaches, or the need to replace GPU's.

Disclaimer: This thread is not an attempt to stop the age old excuse, "But Hon, I am going to have to upgrade my system because it just can't handle the new games coming out". That is an age old excuse that must always be handed down to our children, or handed up to our Parents.

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