I've recently go very strange issue with my Radeon HD 4870 (two and a half years old). Have to tell you that I have never had a single problem with this one till now.
Few days ago run SCII and in few min. my monitor gone off(low power state), restarted the PC and run SCII again - same thing. Then I've noticed that red LED on the back of the card that is on. Google it and found that all 4 red LEDs have to remain unlit, but unfortunatelly second one remains solid red. Light ID: D601 - shows critical Core power fault !? whatever that means.
I've done some tests with GPU-Z and found that the VDDC Curent has rise to ~35A on idle (usualy ~26A) and on load it goes up to 110+ A (usualy did not exceed 69A on furmark)
The only way to fix this is to shut down the PC wait 5 sec. and power it on again. This fixes the red light and the card works fine till next time I switch off my PC for more than few hours. When the PC is being off for a while and I switch it on the red light comes up again and does not matter what I do it will remain until I shut it down for 5 sec. and then switch it on again. (reset does not fix the problem)
This is realy annoying since every morning now when I switch my pc on have to wait for the win to boot, then shut it down and boot again.
I've tried to change the 2 six pin power conectors that power up the card - didn't help.
My PSU is BeQuite 650W (6-7 months old)
Is there someone who can explain what does this "critical Core power fault" mean? And how it is suddenly NOT failing after switching off and on again ?
Or any other ideas that might help ?