Display driver stopped responding and has recovered, faulty GPU?

Hello everybody, I got some problems with my GTX 670 video card, if somebody can help me that would be greate and sorry for my bad english, I hope you can understand me

Full Specs:

MOBO: Asus Maximus IV GENE-Z/GEN3
CPU: i7-3770KK @ 4.2GHz
Cooler: Corsair H100
RAM: 2x4GB Corsair Vengeance 2133MHz CL11 Rev A
GPU: Asus GTX 670 DirectCU II
HDD1: 2TB Seagate Barracuda - 7200rpm, 64MB, S-ATA 3 - (Windows 7, Windows 8.1 Preview)
HDD2: 1TB Western Digital Caviar Blue - 7200rpm, 64MB, S-ATA3 - (Windows 8.1)
PSU: Corsair TX650 v2

What happend:

So, about 2 weeks ago my graphics card started to do some wierd things like I played some games then suddenly a black screen show up (monitor signal lost) then turned back and crashed to desktop with a nice message that my Display driver stopped responding and has recovered, after that day I started my PC and I only opened Google Chrome and same things, and its started to repet it again and again and I could not do anything need it to restart, this happend with Windowsw 8.1, now its unusable, but not Im writing this on my Windows 7 (cuz I got a secondary OS for backup, also btw the two OS is on a seperate hard drive just to know) and here everything look fine at the desktop but If I start a game its just minimeze to the taskbar and I can't open it, others just run but if u start something graphically heavy like its running okay on a 2D menu, but if u start it or having a 3D menu its just do the same thing black screen (monitor signal off) then back the message...

What I have tried:

-tried all of the avaible drivers from nvidia for this card, complety uninstalled drivers and reinstalled and tried all of them, no luck
-removed the GPU, cleaned the dust (but it was really little), made sure fans are working fine
-checked temperature, its running on idle 30-40 C and while doing something heavy like games (if I can) its about 60-70 C, also no overclock (maybe stock oc)
-tired my friend R9 270, worked like how it should, so nothing is wrong with my other components in my PC
-tried placing the card to an other PCI Express slot, same thing there
-tried to connect the GPU to my monitor with an other DVI port and HDMI too

What I want to know:

-what is the problem with it? (this is the obvious one)
-what program should I use to fully diagnose my PC when I do this and give a log from it so I can share it here and you can analyse it more easily
-is this really the sign of my graphics card is faulty? if yes what should I do, can it be repaired?

Some other info:

-on my Asus GPU Tweak app its says:
GPU Boost Clock(MHz) = 0980
Min. GPU Voltage(mV) = 0987
Memory Clock(MHz) = 6008
Power Target(%) = 0100
Fan Speed(%) = 0010
-I overclocked really long time ago, I don't really remember how it is down by now, so thats why I writed down all of the details just to know, some people says it can be downclocking...
-drivers Im now using: 344.11
tried: 337.88, 337.50, 335.23, 332.21, 331.58
-also I have tried it on a not really used Windows 8.1 Preview OS where nothing really was installed and same thing as in Windows 8.1 (full) can't do anything even on the desktop, so I don't really think it is the OS, but yeah I don't tried it on a newly installed one...

THE MOST IMPORTANT THING WHAT IS REALLY-REALLY INTERESTING AND WIERD:

...is that Call of Duty Modern Warfare 3 is just running fine, like what the hell? Im asking...
Seriously...I can max it out with no problems 100 FPS+ while I can't even find any other single game that even run, so Im saying its must be something softwarely wrong not hardwarly...but I never seen something like this before, and Im really hoping that this card can run longer then 2 year, and I hope somebody here can answer for all of this questions and I can wake up from this nightmare

Really thankyou for reading to the end