We all know that with a Windows machine it is easy to overclock a video card, and there even exists software solutions to help one do so. OS X, however, prevents access to such settings, making our only option a firmware flash. We looked at the Mac firmware of the 8800 GT and have found the hexadecimal sequence as follows: (64 69) 58 02 DC 05 84 03 It is unique and contains 3 frequencies of the video card, the figures in brackets were there only to ensure that the sequence is unique. To read them, we must reverse the pairs of values, as was the case seven years ago when we learned how to overclock the first GeForce 2 MX. Ahh, memories… The first value, 5802 is the hexadecimal value 0258 (or 600 base ten) is the frequency of the GPU. The second value, DC05 is the hexadecimal value 05DC (or 1500 base ten): it corresponds to the frequency of scalar processors (ROPS). The last value, 8403 corresponds to the base ten value of 900 (0384 in hexadecimal): it corresponds to the frequency of memory (1800 MHz DDR3). To overclock the card it is enough to simply tweak these values. We tested it by pushing the GPU to 650 MHz, the ROPS to 1650 MHz and the memory at 950 MHz (1900 MHz DDR3). The sequence hexadecimal then becomes: 64 69 94 02 72 06 B6 03 These values were not chosen at random. We checked the stability in Windows via BootCamp. Obviously, we did not try to push the card to its limits, since it would have been very difficult to flash again blindly. To edit the firmware, we used the good old Hexedit, and calculated the hexadecimal with the system calculator. Once the special firmware was registered and verified in several instances (a mistake would bring heavy consequences), we used the flashing procedure described in the article on The flashing of the 8800 GT PC to update the card. Due to time constraints, we have achieved only one bench to confirm that the overclock went well. We used GLview 3.0 to test Open GL performance of the video card. The results are shown below obtained at 2560x1600 resolution. Top: results of the 8800 GT at base frequencies. Bottom: Results of the same card, overclocked. The gain in performance, as can be seen, is 6 to 8% depending on the version tested Open GL. In the future, we will seek to push the card as far as possible. WARNING! Do not preform this unless you are an experienced user as this operation is risky! We attempted it purely for the joy and challenge of overclocking, knowing that we had a backup card to take over in case of a serious problem, or be used to restart the flashing process. [translation by CliveAtFive]

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	www.hardmac.com/news/2008-02-28/#7869