The recent upgrade was the 6850 and the PSU. Previously I used the onboard motherboard graphics (Radeon 4250) and a no-brand 300W power supply. This worked fine until just before the upgrade, whereby first I noticed graphics artefacts in every game: odd polygons sticking out of the ground and people’s faces. Weird. Around this time the computer also started completely freezing: but this only happened in windows, and not in safe mode. I’ll be honest and say the computer was a bit prone to overheating and switching itself off after a few hours of Mass Effect 2 at this point. I felt I may have frazzled the onboard graphics, but I was after a new card anyway so I bought the 6850.
So for a week I’ve had no problems. It’s been a dream with the 6850. But yesterday the freezing started again. At first only about once an hour (and would need a reset) but this morning, more often. Then it did it within a few minutes of me restarting the computer. And now it won’t output video at all, not even to start up. I was hoping to god it was a windows thing but in that time it was freezing both in windows safe mode and also on the startup screen before BIOS, once. It’s hard to feel like the freezing and no-video are unrelated.
I’ve tried lots of things since. Taking the graphics card and seeing if it outputs on the onboard. Taking everything apart from CPU, ram and motherboard out. Resetting the CMOS. Reseating everything. Making sure all the power cables are plugged in. Nothing’s working. The fans all spin but no video.
I have a question about posting. People say I should hear a beep – is this only if a motherboard speaker is connected? I have one, but I’ve tried lots of times to work out where it plugs in – I came to the eventual conclusion that my motherboard doesn’t have that facility. Is that ridiculous? Here’s a diagram of the motherboard from the manual: http://dl.dropbox.com/u/3648716/E5834_M4A88T-I%20Deluxe...
9 times out of ten your motherboard speaker header will be located near the power switch header and have four prongs two of which are actually used. it sounds to me like your mb overheated and continued to degrade over time.
I've had basically the same exact issues as you this past weekend. I've done basically about everything to buying used gfx card, hdmi cord, testing the PSU with a multimeter, replacing the CMOS battery, breadboarding... I wasn't getting any beeps either.
Couldn't check my processor, but I'm pretty convinced my MB died on me so it may be the same for you.