I heard many questions about PCI Express; what works with what, what doesn't work with what, what are the different generations, what does it all mean. Today we are going to tell you everything you need to know about PCI Express 3.0 as precise as possible.
PCI Express is the interface that is used to plug modern expansion cards into modern computers or motherboards. 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 all pretty much fit as long as you are aware about these simple guidelines. Now I said the universal but PCI Express slots are available in a variety of different physical configurations. The most common ones are 1x, 4x, 8x, and 16x. All these types have different slots on the cards themselves and different slots on the motherboard. The cool part about that is that they are upwards and downwards compatible.
I can plug a PCI Express 1x card into a 16x slot. It gets the same power delivery. it just gets less bandwidth delivered to it because that's all a sound card actually needs and not only that, I can take this PCIe 8x card and plug it into a PCIe 4x slot. It will still work but it will only have half of the bandwidth available to it that it would have otherwise had if you plug it into an 8x slot.
The other thing that affects the performance of a PCI Express is the generation. I tested a PCI Express generation 2 16x card and a PCI Express generation 3 16x card. They look physically the same on the connectors but the actual available bandwidth has doubled. In fact the available bandwidth the PCI Express cards has doubled with each generation, so PCI Express generation 1 at 16x slot is only equivalent performance to a PCI Express generation 3 4x slot.
The takeaways from this are straightforward; PCI Express cards work in PCI Express slots as long as there is nothing physically in the way. Performance on the other hand is going to be dictated by what generation of PCI Express the card and the slot are running at. It will run at whatever is the lowest generation divided the two components. Gen 2 card Gen 3 slot, putting together, they run at Gen 2 and performance is also determined by the length of the card and the length of the slot.
For example, this quad port Gigabit NEC needs at least 500 megabytes per second of bandwidth in order to operate at peak efficiency. That means if I have an older PCI-E Gen 1 motherboard, I'll need at least a 4x slot or hypothetically 2x slot to get the bandwidth I need. This is because it is only 250 megabytes per second on a 1x slot. However, if I have a PCI Express Gen 2 motherboard, I could even use a 1x slot to get everything I need because that'll be about five hundred megabytes per second.
It is always recommended to use the latest generation graphics card with a compatible (same generation) PCI Express slot on the motherboard to take advantage of the speed and effects of the latest technology.
