i recently bought a sapphire 6870, swapping out my 4850. after making the switch, i realized that the 6870 was not recognized at all by my computer. only by running the onboard video could i get to the desktop. i tried everything i could think of - updated BIOS, updated windows 7, reformatted, installed drivers. finally after much turmoil i went to sleep for the night, only to wake up and find that windows could now magically recognize the card. so, i installed the drivers, ran a few games to test it out, and everything was great. after testing i went back to windows desktop and left to run some errands.
well, after getting back, i find the computer shut down. not good. turning it on, i hear the video card fan spin at 100%, and does not reduce speed in a few seconds. not good. and, lastly, of course, there is no input from the monitor. so, i'm back to square one...running off the onboard video.
the slot works, as i've put my old card back with fine results. i've tried taking sticks of ram out, to no avail. both power connectors are connected to the gpu. no option to disable onboard video in BIOS, only 'enable if no ext gpu'. i'm just at a loss, as obviously it works but something is just not registering.
i'm guessing its an issue with BIOS, because it seems not to be detecting it even prior to windows booting. but i'm at a loss as to what - like i said, the BIOS has been updated to its current version. any thoughts would be much appreciated.
well, OK. it seems to be related to a power issue. after i pull the power and place the switch in the 'off' position on the psu, the gpu is now recognized. strange. glad i didn't have to spend 6 hours figuring that out like last night. oh well....hope this helps someone else