The PCIe bus is becoming the dominant interface on PC Motherboards nowadays. With this current advancement in the technology, the PC-based DVR industry was driven to adjust and adapt to the improving and fast-paced PC world. Thus, the entrance of PCIe DVR Cards into the CCTV scene.

Most of the DVR Cards available in the CCTV market today are still referenced to PCI. But how long will the PCI technology last? How long can we make use of our PCI DVR Cards? New motherboards are introduced in the market almost every month like crazy. Having said that, it won't be a big surprise if the PCI technology gets obsolete before we know it. This is where the industry is headed to and we have to face that fact. The PCI DVR Cards will soon be replaced by PCIe DVR Cards. And it's for the better. c",)
Why we moved to PCI Express?PCI Express has several advantages, not only to the users but to manufacturers. It can be implemented as a unifying I/O structure for desktops, mobiles, servers and workstations, and it's cheaper than PCI or AGP to implement at the board level. This keeps costs low for the consumer. It is also designed to be compatible with existing Operating Systems and PCI device drivers.
PCI Express is a point-to-point connection, meaning it does not share bandwidth but communicates directly with devices via a switch that directs data flow. It also allows for hot swapping or hot plugging and consumes less power than PCI.
However the most promising feature is that it is scalable meaning greater bandwidth can be achieved through adding "lanes," ostensibly future-proofing into the next decade.
While we've spent plenty of time and energy improving the speed of processors, memory, and other parts of the PC, we've done virtually nothing with the main connection betweern many devices - the PCI. As such we are stuck with a technology in our PCs and Servers that still runs at the speeds and bandwidth we were comfortable with in the 90's. PCI as we know it is holding us back - it is a bottle neck - a limitation to the maximum performance of our systems.
We all want the most from our PC. To get the most out of our PC we must remove all bottlenecks (obstacles to performance). To that end we must turn to the next best alternative: PCI Express.
Increased bandwidth can be equated into increased system performance. We've long known that to get the most out of your processor you need to get as much information into it as possible, as quickly as possible. Chipset designers have consistently addressed this by increasing Front Side Bus speeds. The problem with this is that front side bus speed increases the speed of transfer between the memory and CPU but often you've got data that's coming from other sources that needs to get to the memory or CPU like drives, network traffic, video, etc. PCI Express addresses this problem head on by making it much faster and easier for data to get around the system.
References:
http://www.wisegeek.com/what-is-pci-express.htm
http://www.directron.com/expressguide.html