Extended desktop problem, monitor won't boot!

Hello,
First of all, I highly appreciate any help I can get through these forums. My problem is so stressful that anything would be good atm.

Ok, so my problem:

I can't get extended desktop to work since I have Windows7. It allways worked flawlessly on windowsXP pro and I used it on windows7 aswell for a little while.
But all of the sudden my second monitor won't boot from hibernation correctly anymore.
When I turn on extended desktop, my second monitor will boot and everything seems to be working perfectly, but unfortunately this only lasts for a couple of seconds before the monitor goes to black again. Windows still sees it as a working monitor and I can drag stuff on that screen.

There's a huge list what i've tried allready:
- Changing monitors and cables ( tried 3 ).
- Dual-link and single-link DVI connectors.
- Updating ATI drivers from 9.7 up till 10.9 ( current )
- Format windows 7
- Checking resolution and hertz
- Replacing the PSU ( old one died, new psu has 200Watt more and runs on 700 and should be enough )

From this point on I contacted a Club3D tech:
- Bios flash to latest version
- Motherboard chipset drivers updated
- Clear CMOS

The Club3D tech analysed the problem and thought it was a timing issue in the graphics card and told me to send it in for repairs.

The card has been tested on:

Benchmarks: 3dmark06 2560x1600, 3dmark vantage 2560x1600.
Monitors: native DVI Dual link monitor 2560x1600, Native D-sub monitor 1280x1024, Native Single link monitor 1920x1080.

OS: Windows XP SP3, Windows 7 Ultimate.

Drivers: ATI Catalyst 10.5, ATI Catalyst 10.8.

Result:
Card was working properly, no defects found by Club3D.

Bad decission:
So then I thought, well.. it has to be my motherboard. And I was so certain about that, that I bought a new motherboard and a second graphics card aswell ( for crossfire purposes ) but I installed the new hardware today and when I booted windows I got disappointed with the same boring old extended desktop problems. I realy hoped buying the new motherboard would solve the problem

Conclusion:
So I now know it aint my graphics card, it aint my motherboard, the screens work fine, the dvi connections work fine.. i've tested and tried everything I know that can be tested. Only items that haven't been tested or replaced are the memory banks and the CPU.. I mean.. what else can cause these problems?

I realy have no idea what to do anymore, i'm stuck and I need help desperately! I've allready spend 200 bucks on hardware that didn't even solve the problem!

Movie made with phone to show what the screen does:
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What did I miss? What can cause dual-screen boot issues? Everything else works perfectly fine, except for multi-screening.


Many many thanks in advance for anyone who can assist me!

Thanks for the super fast reply!

Well, all screens work perfectly when they run as the main monitor. All 3 fail as soon as you try to run them as the second extended monitor. So the most logical thing to think would be bad drivers or a broken videocard.. but this has all been tested and it seems that it's not the problem.

Also something that used to help was, turning the second monitor on/off untill it stayed on. This could take up to 40min, but eventually the screen would stay on and work.. nowadays ( 2 months after ) even this doesn't work anymore. Again, makes you think it's graphic card related but this is 100% impossible and it has to be caused by something else.

Do you think this can be caused by the CPU or RAM? That is the only thing untested, tho I wouldn't know why the CPU or RAM would have anything to do with display issues.

Oh no sorry, you misunderstood. I tried 3 different monitors to work as the second monitor, I don't actually work with a 3 monitor setup. Just to show that it aint the monitor being faulty

Card has been send back to Club3D, tested in several systems, on several monitors etc etc without any problems. Also, i'm running on Crossfire now and my main graphics card is the new XFX HD4870 and not my older Club3D HD4870 card. So unless the test results of Club3d are faulty and both graphic cards are broken I highly doubt that's the reason

The card doesn't have any problems, it has been tested by Club3D technicians in multiple test setups. Problem is caused by something unrelated to the graphics card.