Creative has shed some light on problems surrounding the company's X-Fi sound cards. Since the X-Fi's introduction last year, some users have reported problems with the sound card that are reminiscent of glitches associated with the SoundBlaster Live! a few years ago, namely motherboard compatibility issues, sound popping and crackling, blue screens, and system lockups. Here's an excerpt:

Before moving into the specific detail of our findings we feel it would be helpful to cover off some background information on how audio is handled and delivered in a PC system. Firstly it is important to understand the significance of system memory and relationship between it and the audio card. System memory is in fact the source of the many building-block streams of audio data that a sound card receives from a game or other application. Most importantly a sound card that is designed to significantly enhance and process system audio has a fundamental requirement for quick access to this system memory. Audio streams are continually being read in from system memory to the sound card, and the Creative X-Fi chip processes and mixes these streams into the final multi-channel output. The sound card does have on-board storage that allows it to tolerate being held off from memory access for some amount of time, and in fact, this tolerance for being held off, which we call latency tolerance, is higher for Sound Blaster X-Fi than it was for previous generations. At the same time, the enhanced capabilities of Sound Blaster X-Fi require that it read in a larger amount of data than previous generations of sound cards, although much less than a graphics card or hard drive requires. The impact of a delay in receiving data to a graphics card is slower frame-rate, whereas to audio there is a far more significant impact. Because audio is so "real-time" any delay in receiving data causes a break in the audio stream and this break translates to pops and clicks in the audio stream.

So now to our findings: We believe that the larger volume of data being requested is, in some systems, causing larger access delays to system memory, especially when Sound Blaster X-Fi is sharing memory access with high-end graphics and/or hard drives. We have found that with certain high-end systems and configurations, Sound Blaster X-Fi is being held off from receiving data from the PCI bus for significant periods of time, in some cases for close to two-thirds of a millisecond. This causes our audio buffers to underflow, which produces crackling sounds. The obvious answer to this would be to increase the latency tolerance, but due to the requirement for audio to synchronize accurately with graphics, we cannot increase the latency tolerance beyond a certain point.

Our tests have proved that in many cases these problems can be remedied with a simple BIOS update but this did not resolve the issues for all customers experiencing the issues. We therefore continued to investigate and have made a significant finding. In some systems we have resolved the issues by setting the motherboards to dual-channel memory mode to improve the memory bandwidth and response. Below you can see the configuration of two of the systems that we initially experienced issues with and subsequently resolved by setting to dual-channel memory mode.