Poor Graphics Display - ATI Radeon HD4850 - Windows 7 on 27" iMac

I'm running Windows 7 on a 27" iMac using an ATI Radeon HD4850 graphics card. 

The problem: rather than smooth gradients between colors, the graphics are "stepped" or striated. ie. rather than a grayscale gradient smoothly transitioning from black to white, it steps through a series of gray tones from black to white. 

Using ATI's Catalyst control center, I can change the color quality from High (32-bit) to Medium (16-bit) and this affects the gradient, but is still not a smooth transition. 

On the Mac OS side of the machine the graphics are beautiful.

I've tried everything and called everyone...please help me. 

Thank you


Question Info

Last updated April 15, 2018 Views 1,668 Applies to:

Hi Rmholl,

Try these steps.

Step 1


Step 2

Uninstall catalyst control center

A.   Click start >> control panel >> Programs

B.   Right click the program and choose uninstall

Step 3

A.   Click start, type “devmgmt.msc” in the start search box and press enter.

B.   Expand display adapters, right click the driver and choose “uninstall” (Make sure you check the box for “Delete the driver software for this device”

C.   Download the install the latest drivers and install.

D.   Check the display.


Bindu R - Microsoft Support
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