There has been a lot of buzz around the web regarding an article published by W1zzard over at TechPowerUp. He found an irregularity when testing the just launched GeForce 9600GT. It seemed that the card would perform exceptionally better when it was running with an overclocked PCIe bus, which isn’t normal under these circumstances. He investigated it further and found that it seemed like the card used the PCIe frequency as a reference crystal, instead of the on-board physical crystal. A follow-up investigating the oddity was also posted.
The problem with this isn’t so much that the card overclocks with the PCIe bus, it’s actually quite nifty, but that the increased frequency wasn’t reported by the drivers. The card seemed to operate at default frequency when it was not. People have been wondering why NVIDIA didn’t reveal this to people reviewing the card, as they may have been lured into making the card look better than it was. That would be the paranoid angle of it, but right now it’s the one dominating the discussions.
We still don’t know why this information was omitted. It might just have been some sort of miscommunication at NVIDIA, because it has now made an official response saying that the card does indeed have two crystals. One on-board 27MHz crystal and one crystal which is connected to the PCIe bus. The things is, GeForce 9600GT isn’t the only card that behaves this way. TechPowerUp discovered that GeForce 9800GX2 behaves the same way, and chances are that the rest of the GeForce 9 series cards do too.
