The case of the disappearing 2nd monitor Asus P7P55DE_LX + GTX260, GTX760

[V8Bill]

Ok folks, this one's got me beat. All of a sudden my 2nd monitor's not being detected in Windows (XP or 7). It was previously working fine but I bought a new GTX760 and since installing it I've lost my second monitor.

The story:
Up until recently I've been running a dual monitor setup out of a GTX260 running on an Asus P5E board which I built way back in 2009. Windows XP Pro was my home but well, eventually I was dragged kicking and screaming into a new setup by the board's inability to recognize a 2TB WD Green HDD.

So I bought a new second box with an Asus P7P55DE_LX board. I bought 16GB of DDR3 and a new Intel 250GB SSD. The machine was already running with Win7 Pro64 on a 1TB WDD drive but I wasn't quite ready to move to Win7 because I still had some preparations for migration so I installed and configured my existing XP drive with my old GTX260 card with dual matching LG Flatron IPS225 monitors.

Everything was running fine, both monitors were working. The old XP system took to the new motherboard just fine after loading all the new and latest drivers including the newest GeForce 340.52 driver. a few days ago I bought a second hand GTX760 (mostly for it's HDMI port as the 260 didn't have one) but also for a small boost in performance.

Today I decided to install the newly acquired GTX760 but once installed I lost my second monitor. I have done everything I can think of to get it back but nothing I've done has made it visible to windows. Eventually I changed back to the GTX260 and now I can't even see the second monitor on that! WTH?!

Things I've tried:

• - Both monitors work fine when plugged into the primary digital port.

• - No monitors work from the secondary digital port.

• - I've checked and changed both digital monitor cables and am using a brand new digital cable for the second monitor.

• - I have a powerful Corsair HX620w Power supply with an 8 port PCIe cable which I use in the GTX760.

• - I've been using the 6ports of the PCIe power plug for the GTX260 (which needs 2 power supplies of 6 ports each) plus a second Molex-to-6port PCI power plug. It ran fine and displayed both monitors before I switched to the GTX760 today and lost the second monitor.

• - I've checked the BIOS and updated to the latest version even though I was already running the latest version.

• - I even disabled the Marvel SATA controller and am now running all drives off the standard (blue) Intel ports. I have 5 drives. My XP drive (320GB WD), The original 1TB Win7 WD drive, The Intel SSD drive (currently empty), the large 2TB WDD Green and my old Pioneer DVD burner.

• - I've reset the BIOS to default as well as gone in and checked and adjusted boot screens, drive boot orders...etc

I'm totally stumped. How could installing a GTX760 affect the second monitor? How could the 2nd monitor still be lost when returning to a working dual monitor GTX260 card? My feeling is that it's something in the BIOS that might be preventing the PCIe slot from detecting the second monitor because both cards are working fine in both XP and Win7 with all the latest drivers - just no second monitor.

What have I missed? Any suggestions are appreciated. I even rang the seller of the GTX760 and he swears that he was running a dual monitor setup out of the two digital ports just hours before taking the card out of his machine and selling it to me. Tomorrow (or while I'm waiting for suggestions from you guys) I'm going to ask him if I could come back and see the card working with dual monitors just to be sure but if it was the "new" card why has the old working card suddenly lost it's ability to view the second monitor?

 

[V8Bill]

Update.

I swapped out the motherboard for a Gigabyte GA-X58A-UD7 with an i7 and a new power supply (850w). So now it had another motherboard (eliminating the motherboard from the equation) and new power supply (eliminating the power supply from the equation) and STILL no second DVI monitor!

WTF?!!

You know that silent rage that explodes inside you and yet you maintain a straight face?

So, it can't be the motherboard, it can't be the power supply, I've tried 3 different cards and nada, zip, zero, nothing, no way Jose, no second DVI in my life or future.

Both monitors work fine when connected individually to the primary DVI port (the port that works) on all three cards. I've swapped DVI cables for an old one and two brand new ones so it's not the monitors and it's not the DVI cables and it's not the motherboards and it's not the power supplies.

I've also tried it on two different operating systems (including a brand new install of Win7 Pro 64) on two separate hard drives and nothing.

The universe is determined to not allow me to use two monitors no matter what I do. 'king bizarre!

How can EVERYTHING be isolated and changed and yet still can't get twin monitors set up? How is this possible? This can't be happening.

I actually exploded on the weekend - completely lost it. Removed the Gigabyte motherboard and took a hammer to it - smashed it into a million pieces - chucked in the bin. Took the GTX260 out and while the hammer was hot - took to it as well. I figured "why stop there?" so I took the hammer to the GTX760 as well and smashed it to pieces and while I was at it - brought cold death to the GTX680. Why waste all that energy right? I was on a roll.

I calmly reinstalled the P7P55DE_LX the i5 with the original crappy 1 x DVI + 1 x VGA and resumed my dual monitor operation in piece and calm on XP.

Then two days ago I just had to try again because it was eating me up inside so I bought an old school 8800 GT Alpha Dog which I thought might work being so old. Not only did it have a screaming loud fan but again - no second DVI out.

This time - no smashing because I went into zombie mode. Removed it nicely, packed it away in my box of old useless hardware and resumed operation with the trusty shitty ATI Radeon 4300/4500 and am back on DVI + VGA dual monitor. I can resume my work but there will be no games anymore for me.

That is all. End of story. No solution was ever found.