The nForce4 chipset has also been blamed for issues with PCI cards, relating to Nvidia's implementation of the PCI bus. RME Audio, a maker of professional audio equipment, has stated that the latency of the PCI bus is unreliable and that the chipset's PCI Express interface can "hog" system data transfer resources when intense video card usage is occurring. This has the effect of causing audible pops and clicks with PCI sound cards. Gamers have noticed this effect, especially with Creative's Sound Blaster X-Fi and Sound Blaster Audigy 2 sound cards. Compatibility issues between these sound cards and nForce4 motherboards have been ongoing, including reports of serious and irreversible damage to crucial motherboard components. Driver updates were also found to be unsuccessful. Latency issues are more readily apparent with sound cards than other addon cards because of the direct user feedback the audio problems demonstrate.