PC Freezes Crossfire PSU doubt

My system is freezing !! D: with crossfire, anyone knows why is happening? it worked fine yesterday but after disabling "frame pacing" it all began to explode.

With Cross activated, after one or two minutes of loading a game, THE SYSTEM CRASHES and i need to reboot manually, i had uninstalled the 14.1 Drivers and installed the 13.12 but the problem still present.

I had done anything related with the driver, but the problem persists. the both cards have months of life
xfx: 5 months and the asus has 3 Please help me to figure out what is the problem with my computer.

Mobo: GA-990-FXA-UD3 Rev 4.0
Proccesor: FX 8320 (Without OC)
RAM: 8GB two sticks DDR3 ADATA at 1600mhz
Video: Two 7850 (Crossfire) of different brand ASUS (GPU1) and XFX (without OC)
2 HDD: One 2tb (Seagate) and 320gb Western Digital
and 1 DVD R+RW device
5 LED fans 120mm
625 PSU Cooler Master Extreme 2

Windows 8 64 bits

10 days before i had one FX-6300 no problems with it.

Now that i've installed de FX 8320 the problems began but the strange thing is that for days all was fine.

I will describe you all the steps that leaded to this point:

First of all i have Windows 8 Pro 64 bits installed since i tried to install te 13.12 Drivers 2 months ago the problems began at the middle of instalation, specifically on the "installing display driver" BAM a BSOD with the legend blaming atikmdag.sys i know some of you are thinking right now: You need to expand the atikmdag.sys file with this method:
FIX BSOD ATI Blue screen on atikmdag.sys solved fix

YOU NEED DO IT
Driver Sweeper DONT WORK AND DO NOT DELETE ALL FILES

YOU NEED DO IT EVEN IN A FRESH COPY OF WINDOWS 7 IS INSTALLED

– Step 1: Download and install the latest ati graphic driver.

– Step 2: Then go to C:\Windows\System32\Drivers and rename atikmdag.sys to atikmdag.sys.old.

– Step 3: Go to ati directory (usually in C:\ATI) and find the file atikmdag.sy_.

– Step 4: Copy the file to your Desktop directory.

– Step 5: Open cmd.exe by going to Start -> type cmd in the search box and hit enter.

– Step 6: Change the directory to Desktop by typing chdir Desktop.

– Step 7: Then, type EXPAND.EXE atikmdag.sy_ atikmdag.sys. Or,
expand -r atikmdag.sy_ atikmdag.sys

– Step 8: When the expansion is complete, copy the new atikmdag.sys from your Desktop to C:\Windows\System32\Drivers

– Step 9: Restart your computer and the problem should be resolved.

THIS WORKED FINE for a while. The 14.2 driver came up and i had to do the same thing 'cause the problem with BSOD had returned in the same point of installation. i did the same thing again described up this lines.

And worked again BUT after days of this instalation i decided to modify an option in Catalyst
AA Morphological from off to on. And played for a while COMPANY OF HEROES then suddenly when i tried to play BF4 with AA Morphological activated the PC crashes. Not a single sound, NO BSOD only STOP RESPONDING, LEADING TO A FORCED RESTART.

WHEN i tried to play it again ANOTHER FREEZE...EVEN watching Youtube Videos opening 9gag.com

I'd uninstalled drivers an tried the 13.12 Drivers and the Freezes came again. so i uninstalled again the drivers. But THE PROBLEM PERSISTS

(THINKING THAT I MESSED UP MY COMPUTER DOING THE MODIFY TO THE ATIKMDAG.SYS FILE) I DID A CLEAN WINDOWS 8 installation and the problem is back FREEZES AND FREEZES

I THINK MY PSU MAYBE IS THE CAUSE

i already removed the XFX card and appears to work fine...but i dont have the drivers soo i cant play games to try it even more please give me some advices

Even when i uploaded this cuestion with ONE CARD CONNECTED THE PC CRASHED THE SAME WAY