14 DAY TRIAL // The 9600 GT offering from Nvidia has been around for a while, but many of the users were amazed by how well it performed in its early benchmarks. In fact, it performed that well that it easily beat its older[admark=1] brother, the 9800 GT, despite the fact that the former came with only 64 shader processors.
It seems that the secret recipe for the mid-range killer is the fact that many of Nvidia's manufacturing partners would release factory overclocked cards. In fact, some of them have released extremely overclocked versions that would become unstable when reaching high temperatures, and downlocking the cards were the only solution to make them work. Downclocking may seem at least funny, given the fact that enthusiasts are usually concerned with the other way around, but having an useless high-clocked card is just an expensive piece of rubbish.
Additional investigations revealed that there are discrepancies between the frequency the driver is reporting and the frequency reported by the clock generator. The answer is simple and involves the physical crystal on the card: while it has a 27 MHz clock, the driver is using a value of 25 MHz in order to calculate the GPU frequency.
Further testing shows that the chip manufacturer designed their graphics processor in such a manner to take the PCI-Express frequency and divide it by four in order to get the crystal frequency. Overclocking the PCI-Express bus will lead to an involuntary overclock of the graphics processor, but at the same time, the driver will still report the standard GPU clock. For instance, raising the PCI-Express bus from 100 to 104MHz will make the GPU beat at a faster pace, from the default 650 MHz to 676MHz. Despite the higher frequency, the driver will still "see" the card as operating at 650 MHz.
This may be regarded as a hidden overclock performed by Nvidia, and many users out there are "riding" highly overclocked versions of the card without them even knowing it. However, there are some issues that could render the graphics card useless with no apparent reason. For instance, there are various motherboards that clock the PCI-Express bus automatically, such as the LinkBoost feature in Asustek's Striker Extreme. Overclocking the bus by 25 MHz could be fatal for the 9600GT graphics card.