Second monitor no longer detected after new GPU installed

[RedInsanity]

I recently bought a GTX 1080 EVGA FTW. I have two monitors, the gtx 1080 has 5 ports - DVI-D, 3xDisplayport, 1xHDMI.

My main monitor VG248QE works perfectly fine on the DVI-D connection, however, my second monitor an old LG W2240 monitor is using a VGA-> displayport adapter and then into the graphics card. This solution worked perfectly fine for me before with my GTX 760. Using completely the same setup. Both the monitors are 1080p (1920x1080).
Now when I first got my gtx 1080 and plugged in my LG monitor (with VGA->DISPLAYPORT adapter) it worked for 2-3 days, completely fine, plug n play - it was perfect... So after a few days passed then suddenly it goes black and starts displaying "Check signal cable." It has been doing this continuously over a week now - I have nearly tried everything in my power to correct and fix this issue - Things I've tried are:

My setup:
Main monitor - ASUS VG248QE
Second monitor - LG W2240
CPU - i5-2500k
MOBO - ASUSTeK P8H67-B3 rev
Memory - 4x4GB RAM running at 1333MHz (no xmp in mobo)...
GPU - GTX 1080 EVGA FTW
Storage - 2HDDs and 1 SSD for windows
Windows 7 ultimate

Troubleshooting
1. Power PC down, unplug monitor wait few minutes, press the power button of monitor to discharge the caps, then replug and try it again - didnt work.
2. Completely erasing NVIDIA drivers and reinstalling them from fresh.
3. Resetting bios by removing the motherboard battery.
4. Unplugging the PC and trying to discharge its caps then replugging again.
5. Various driver installments and tests
6. Testing the monitor cable - it works perfectly fine on my other PC with my old GTX 760 & on my laptop as well.
7. Testing the displayport adapter, same as above.
8. Trying different displayports on the GTX 1080.. same result..
9. Doing a thorough RAM test with memtest86
10. Many combinations of plugging in only my LG monitor or my ASUS monitor then powering on and so on to try and reset the EDID - to no avail though...
11. Buying a new displayport adapter - same problem.
12. Installing drivers for my second monitor, LG W2240 - didn't work either.
13. Trying to reseat the graphics card and test it in games / furmark and such - it works perfectly fine.
14. Switching my RAM around also trying with only one stick
15. Tried to disable integrated graphics in mobo - but i have non - So no, the cable isn't plugged into the motherboard xD

I read somewhere that the gtx 1080s only support digital signals, and I know that VGA is analogue (if I'm correct all VGA-> displayport are active adapters tho) - however, since my given solution worked for a few days without a flaw then I don't understand why it suddenly would stop to work.

I am using the newest NVIDIA driver 372.70, and have also tried to rollback to older ones where I knew the setup should work.

Also, when I installed the new GPU everything was working fine and nothing was changed. I had a previous version of NVIDIA drivers (368.81) and updated to the one listed above - The monitor worked fine after the reboot and installation.
One last thing - When looking in device manager my ASUS VG248QE monitor pops up as "Generic PNP Monitor" is that supposed to happen?
I usually do lightboost with my main monitor, and so far it has worked flawlessly and has not in any way affected the LG monitor, though I should add.

Anyone have any ideas as to what has cause this problem? I mean I don't understand why the monitor would work for a few days and then suddenly seize to function?

Any inputs are very much appreciated!

 

[RedInsanity]

I've recently tried to format and go to Windows 10 - The problem still exists.. I've tried to completely take the GPU out before installing and then inserting it after I installed windows 10, however, nothing changed. There was a funny thing tho - After booting I've seen that the secondary screen turns on for a few seconds - like 2-3 seconds and then instantly keeps saying the same message as always "Check signal cable." I've tested everything I know is testable... How can I solve this problem ? It's pretty sad sitting around with two monitors where the other one only serves as a black window...