Possible Radeon 6850 Issue

[deltablade]

Hi,

First post here, but I've been using these forums to help figure out issues with my computers for a while now.

My issue currently is quite strange, and I believe it is a video card issue (but possibly not, I'm stumped). I recently built a computer, and when a single monitor is connected, the screen occasionally goes blank until I hard reset the computer.

The issue has occured while I've had only Steam and a game open, or a browser open, or absolutely nothing open.

The time span ranges from under 5 minutes to over 2 hours of being powered on.

I have Win7HP and Catalyst both fully updated.

I have nothing overclocked.

At the time of posting this, and what makes this strange to me, is that connecting both my monitor and my hdtv to the graphics card solves the issue (0 black screens/crashes/blank screens in a few days of use)

My system:
Sapphire Radeon HD 6850
Rosewill Stallion 700W PSU
Rosewill Challenger-U3 Mid tower
AsRock 970 Extreme4 Mobo
Asus PCE-N15 Wireless Adapter
AMD FX-8150 Zambezi 3.6GHz 8-Core CPU
16gb G. Skill Ripjaws X
Sandisk 64gb SSD
Western Digital 500gb HDD
HP DVD Drive
Windows 7 Home Premium SP-1 64 bit

So far, I've tried:
Reseating the video card in 2 separate PCI-E slots
Using different 6 pin power connectors with the radeon from the PSU
Using both DVI outputs, and the single HDMI output
Using an older dell monitor, as well as my 46" hdtv
Fresh windows install
Fresh catalyst install
Disabling Sleep and Hibernation (just recently I discovered that Hybrid Sleep was enabled, but I have no idea how/why my computer would automatically
hybrid sleep so sporadically and only when a single monitor is connected. I've disabled this as well, now.)
Reconnecting all internal wiring (SATA, USB, Power, Front Panel Audio/USB/eSATA, etc.)
Furmark Stress Testing (passed just fine, with no slowdowns or choppy animations)

Please help. I can't always have multiple monitors connected to my PC. This issue is driving me nuts. Everything else is working (at least everything seems to be working) flawlessly.

Thank you in advance,
DB

 

[Xttony]

May be a problem with your ram or faulty PSU.
Reset the bios and set every setting manually. Do not overclock at this instant.
If that solves the problem then use those settings.
Check all the temperatures, mobo, graphics, CPU. North bridge

 

[deltablade]

All temps check out cool (nothing over 40C unless I'm running Video Card Stress test, then the radeon gets to the low 70s after a while, but stable)

RAM checked and working well.

PSU all voltages within ~0.01 of what they should be when I checked.

Bios reset, updated, set manually, no overclocking. Can't believe I didn't think to check this out.

After getting the bios updated and set, I've let my computer run for over 20 hours now, occasionally running stress tests, and its had no black screening issues.

Thank you very much xttony!

 

[deltablade]

Within seconds of my previous post, I received a flash of colorful vertical bars, for less than a second, followed by another all black screen.

I waited a few minutes to see if it would start to respond, but it didn't.

Any other ideas?