Problem updating Sapphire 5870 drivers

Hi there. I bought my PC back in late 2009. My system is:

OS: Windows 7 Ultimate 64-bit
Motherboard: ASUS P6T
Processor: Intel Core i7 920@2.67 GHz
Graphics Gard: Sapphire HD 5870 1GB
Monitor: LG W2361 V-PF (connected via HDMI)
RAM 6,00 GB

Whenever I tried to update my graphic cards drivers I was facing problems.
Before trying to install the new drivers I run into safe mode and cleared everything was related with ATI with Driver Fusion.
With EVERY updated driver I tried, after installing the drivers the screen gets fuzzy/blurry with a black border around.
I found a solution for the black border via overscan form Catalyst Control Center, but the fuzzy/blurry still remains.
This happened with EVERY driver I tried to install except form the drivers that came with the Graphic Cards CD.
When I connect via DVI I see no black border, but screen is fuzzy/blurry.
On the other hand when I install the drivers that came with the Graphic Cards CD, after the installation the screen has perfect view and the black border doesn't disappears automatically (with DVI or HDMI)
The CD is writing Driver Version 13-011 and through Computer Management-Device Manager-Display Adapters the Driver Version is 8.660.0.0 (with Driver Date 18/09/2009)
As long as my system worked perfect with the CD drivers i forgot the case until I upgraded to Windows 8.
In Windows 8 Pro 64-bit (obviously) I can't install the CD Drivers because the don't support Windows 8.
I downloaded the latest drivers from ATI website but I get the same problem with fuzzy/blurry screen and black border.
I tried a new clean installation of Windows 8 with the same results.

I really need some help.. Is there a conflict between my graphic card and something else? Maybe the monitor?
I spent about 350€ for this graphic card and I can't find any drivers working. I am getting crazy and I have a headache because of the fuzzy/blurry screen.

Thanks in advance.