Interference on analog video output
Analog components can be affected by electromagnetic interference from unshielded components in other PCI and AGP cards. Some graphics cards included with PowerMac G5's, contain unshielded copper coils which can interfere with the analog components of some DeckLink cards. All NVIDIA graphics cards are shielded which makes them a safe choice when working with either analog or digital video. Digital components are not affected by electromagnetic interference and so the choice of graphics card is less important. This issue only seems to apply to PowerMac G5's as all PowerMac G4's appear to have included shielded graphics cards. We have not received any reports of the same problem occurring with Windows PC's but the potential for the same issue exists.
Video is full of technicalities and so it helps to know how to identify electromagnetic interference. On cards such as DeckLink Extreme, which has both SDI and analog outputs, the digital output would be fine but the analog output may show interference if you have an unshielded graphics card in the G5. The interference sometimes appears as diagonal lines marching across the monitor and sometimes appears as a Moiré pattern. In this case, the options to overcome the problem are:
1. swap the unshielded card for a shielded card (esp. NVIDIA) and the problem will go away.
2. use digital outputs rather than analog (but this is not always an option)
3. place the DeckLink SP or Extreme card in slot 4, ie the top slot. This will move the DeckLink card as far away from the unshielded graphics card as possible. Many customers have found this is enough to overcome the problem. Some customers also use another PCI or PCI-X card (eg a SCSI or SATA card) in slots 2 or 3 as this can help to shield the DeckLink card from the electromagnetic interference being radiated from the unshielded graphics card. Many Fiber Channel cards are very small and do not provide adequate shielding compared with SCSI and SATA cards.
