Gamers who run Windows Vista with SLI or CrossFire setups will be happy to know that Microsoft has released a hotfix just for them. The KB945149 hotfix resolves an issue that, in some cases, could cause systems with multiple graphics cards to "perform more poorly than expected" in both games and benchmarks. Microsoft describes the issue as such:
A graphics processing unit (GPU) or part of a GPU link may incur a small scheduling latency on a new Direct Memory Access (DMA) packet. This is true if the DMA packet is submitted to the GPU that has previously run out of work and if another GPU in the linked configuration is very busy. In some scenarios, significant starvation of one or more GPUs in the linked configuration reduces the expected performance of an application.
The hotfix may resolve the problem, but it isn't freely downloadable. Instead, users must visit this page and submit a request to Microsoft's Online Customer Services. The company also warns, "if you are not severely affected by this problem, we recommend that you wait for the next service pack that contains this hotfix."
This patch follows the release of three previous Vista fixes intended to sort out various performance and stability issues. The first two came out in late August and addressed gaming problems specifically, while the third followed in early October and resolved more general issues with system stability and responsiveness.