Just upgraded from a Radeon HD 5770 1GB GPU that failed due to (I think) a pretty shitty atx 450w rsy-645 PSU. I replaced the psu and gpu with the above mentioned parts, but now I'm getting no display through the 6850. I can hear it POST and make it into windows (I think. I'm a novice at this, but I get the first beep when it POSTs and a second after about fifteen seconds when all the peripherals have turned on), but there is nothing on my display. The card is firmly seated in its pcie slot with and is cabled correctly to the psu. I can boot through the integrated graphics with the gpus 6-pin cable disconnected, but I can't get a display through either the card or the onboard when everything is hooked up correctly. Also, the CPU fan is considerably quieter when the gpu is plugged in. I'm not sure if this is normal. Things I've done:
On install, I removed all the old graphics drivers and used driver cleaner pro to grab anything else.
I've tried to reseat the card a couple of times to no change.
Tried the hdmi out and DVI in both slots on two monitors.
The old gpu worked fine except under high stress until it quit alltogether, so I don't think it's the pcie slot, but I don't have another working card to check.
Unfortunately, this mobo only has one PCI-E slot. I have a new pc on the way, but cyberpowerpc is giving me an awful runaround and it may not be in for another week, so I have nothing else to check it in for a bit.
I just bought a 6850, and mine didn't work until I had plugged 6-pin cables into both of the connectors on the card. The manual said you only needed one cable, but I had to use both to start mine working right.