Originally Posted by DriverHeaven review
“In most circumstances we would expect the minimum frame rate found on the ATI Radeon HD 3870X2 to be equal to, or better than an ATI Radeon HD 3870. However, there are conceivable circumstances in which the minimum frame rates of the ATI Radeon HD 3870X2 could be lower. The most obvious case where the ATI Radeon HD 3870X2 could have a lower instantaneous frame rate would be if an application uploaded new information (such as textures or vertex data) to the graphics accelerator during rendering. In this situation the ATI Radeon HD 3870X2 driver has to duplicate the uploaded data, copying the data to each of the GPU frame buffers, which naturally takes more time than uploading a single set of data for a single GPU graphics accelerator.
These circumstances should be rare in practice - as a rule applications try to avoid uploading data during rendering as much as possible as such uploads are known to cause inconsistent frame rates.
An important thing to remember is that if a slow frame is caused by data being uploaded, then the effect will be seen across all graphics accelerators (graphics accelerators with multiple cores will just be affected to a greater degree). The visual result would be a small stutter, probably for a single frame, and if this stutter is noticeable on a ATI Radeon HD 3870X2 it is likely to be noticeable on a single GPU graphics accelerator as well.
In most situations low frame rates are caused by a heavy rendering workload, resulting in low frame rates that are generally seen for an extended period of time. Under these circumstances an ATI Radeon HD 3870X2 will shine, delivering a significantly higher frame rate than a comparable single GPU graphics accelerator thanks to its superior rendering power.”
