PCI Express is the interface that is used to plug modern expansion cards into modern motherboards or computers. It completely replaced PCI and AGP, which is great because AGP was only for graphics cards and PCI had to be used for pretty much everything else.
PCI express works with pretty much anything sound cards, network cards, raid cards, and video cards. They will pretty much fit as long as you’re aware of a few simple guidelines. Now I said universal but PCI express slots are available in a variety of different physical configurations. The most common ones are 1x 4x 8 + 16x all of these have different slots on the cards themselves and different slots on the motherboard.
The cool part about PCI Express is that they’re upwards and downwards compatible though. If I plug in a PCI Express one X card into a 16 X slot, it gets the same power delivery, it just gets less bandwidth to deliver to it because that’s all a sound card actually needs, and not only that if I plug in PCle 8X rayed card and plug it into a PCle 4x slot, it will still work but it will only have half of the bandwidth available to it that would have otherwise had if you plugged it into an 8x slot.
There is another thing that affects the performance of PCI Express is the generation.
PCI Express 2.0 vs PCI Express 3.0
- PCIe 3.0 supports a max speed of 8.0 GT/s (Giga Transfers per second) whereas PCIe 2.0 supports a max speed of 5.0 GT/s.
- The encoding used in the PHY layer of PCIe 3.0 is 128B/130B encoding. But 8B/10B encoding is used in PCIe 2.0.
- PCIe 3.0 involves the co-efficient-based Dynamic Link Equalization phase during the Link training process. But it is absent in PCIe 2.0.
- The Compliance patterns between PCIe 3.0 and PCIe 2.0 are different.
- PCIe 3.0 requires two tests for the Tx. The first test is an electrical test that is similar to PCIe 2.0. The next test is a preset test that verifies that the Tx de-emphasis and pre-shoot are within the limits for all Tx equalization settings or presets.
- There is also an additional package loss test and a couple for more Jitter tests(DDJ etc) for PCIe 3.0 compared to PCIe 2.0 during TX compliance testing.
- The receiver Jitter tolerance test is comparatively complicated for PCIe 3.0 but not for PCIe 2.0.
- To sampling PCIe 3.0 signals more Bandwidth Oscilloscopes are required compared to PCIe 2.0.