Is driver for Radeon HD 4870 updated since 10.6.8?

I wonder if the driver for the ATI Radeon HD 4870 that came with my MacPro Nehalem (4.1) is updated for Mountain Lion.

Currently I work with Snow Leopard.

I have trouble with Photoshop files being destroyed from time to time.

The MacPro Nehalem 4.1 was at service several times.

Graphic Card exchanged 2 times (Radeon HD4870 again).

Logic Board exchanged.

Now again problems...

The GPU set to normal, it will happen - not often and not repeatable, but lets say every 1-2 weeks, I have a file - quite complex 1-4GB 20-50 layers .psd or .tif (LZW) files.

Sometimes it results in only one destroyed layer but often it will affect all layers at once.

At the moment I set GPU usage to basic and wait what happens.

(In one case the destruction happened in a smart filter.

After rerendering it was gone - but only in this single case.

But this made me think it is for shure the GraphicCard.)

Maybe it is the driver.

I searched for updated drivers but ATI does not support drivers for the card for Mac.

So, that is why I ask, if the driver is updated in Mountain Lion...

Any information welcome...

Michael

ATI Radeon HD 4870:

Chipsatz-Modell: ATI Radeon HD 4870

Typ: GPU

Bus: PCIe

Steckplatz: Slot-1

PCIe-Lane-Breite: x16

VRAM (gesamt): 512 MB

Hersteller: ATI (0x1002)

Geräte-ID: 0x9440

Versions-ID: 0x0000

ROM-Version: 113-B7710F-176

EFI-Treiberversion: 01.00.318