The main reason is PCI conflicts. Here are the main sources of such conflicts.
1) Partial or incorrect support of PCI-bus specifications by hardware or PCI-controller. As a rule it reveals as:
a) Device and motherboard incompatible.
b) Device or bus controller work unstable or doesn't work in certain bus settings.
c) System as a whole work unstable because different devices require mutually exclusive bus settings.
Frequently such problems may be avoided by certain BIOS settings, sometimes it could not be avoided. Evidently, to this situation may be related incorrect PCI bus controller programming by system BIOS, incorrect initialization of PCI devices by system and incorrect setting of configuration space. The thing is that PCI device initialization is complicated procedure, related with reading device configuration space and setting bus controller according to data being read.
2) Hardware problems connected to PCI bus arbitration. PCI bus is shared between all devices connected to it. If two or more devices simultaneously require data transfer, by the mean of arbitration it determines which device will be granted the bus access, and which device will wait. At this stage there are a lot of pitfalls related to that some devices can wait for indefinitely long time while for others the time is critical factor. Typical case is incompatibility (sometimes inavoidable) with some SATA, SCSI or RAID-controllers. Other case is incorrect arbitration with one of the devices or bus controller.
3) Problems connected to interrupts distribution. In theory PCI bus specifications allow to share one interrupt line by several devices. In practice it is attended by some difficulties. The PCI bus interrupts support has two layers. At first layer only hardware (bus) involved. At second layer by means of reading and programming PCI-registers selected one or more devices that actually requested interrupt. In this case may reveal mistakes in device driver of one of the devices sharing the interrupt line. If interrupt line is not shared this mistakes stay hidden. Unfortunately, it is insufficient that the driver of necessary device is error free. It is necessary that all drivers are error free for devices sharing the interrupt line.
4) Indirect problems not connected to PCI specifications. First of all it is interference between devices on power supply. The thing is that every digital device (of course PCI devices too) is strong source of noise on power feed and on ground. Also it may be sensitive to noise from other devices when level of noise achieves critical level. The other problem related to power is floating of voltage level depending on power required by this or neighbour device. Also total power demand may exceed the capability of system. Also it may be distortions of signals and signal timings upon connection of other devices to the same bus.
Don't diminish the probability of every described situation. There were all cases in our practice. All told shows the depth of difficulty to diagnose and fix such conflicts. On encountering such conflicts we can provide only general recommendations, as following:
1) Change PCI slot.
2) Try to change IRQ lines in BIOS Setup.
3) Change BIOS settings related to PCI bus.
4) Try to disable or even remove devices one by one to detect conflicting device.
5) Provide good power supply.
6) On application settings in "Video" tab change PCI DMA controller settings.
As for our devices. Of course we do not impose responsibility to others. We do all we can do to prevent such conflicts. Nevertheless, there is a set of factors that don't depend on our efforts:
1) Chipsets are not designed by us. Inspite of that NXP/Trident design the most stable and bug free chipsets, hardware problems are still present.
2) On conflict encounter it is objectively difficult to find the reason and who's that fault.