Here is your new bios for HD4870OCX-512MBs at 795MHz-1100MHz and Clock Limitation is 990MHz-1250MHz. Also, this bin has been modified the voltage’s setting as well so it should be fixed on artifacts issue for certain motherboards. I ran a test via 3DMarks 06 for more than 2 hours with the new bin and did not see any artifacts related.
1) Run "ATIHD4870512MBOCX795-1100MHz.exe” under WinXP/Vista
2) Click on “UNZIP” button to begin
3) Let it run through the flashing progress and wait for a confirmation message then restart your PC and Don’t forget to send us an e-mail for the result. Thanks!