What limits the speed of mini PCI Express:

[PHIL528]

Mini PCI Express has a speed of 2.5Gb/s.

Is it that the port of Mini PCI Express is only capable of 2.5Gb/s or is it the cable that limits its bandwidth?

Thanks!

 

[cub_fanatic]

It is the interface. It is basically like a PCIe 1.0/1.1 x1 slot on a PC. You are getting a single 1st generation lane of PCIe on a mPCIe slot if it is onlu 2.5 GT/s.

 

[PHIL528]

It is the interface. It is basically like a PCIe 1.0/1.1 x1 slot on a PC. You are getting a single 1st generation lane of PCIe on a mPCIe slot if it is onlu 2.5 GT/s.

I don't really understand what you mean by interface. The example I was trying to understand this from was that a thunderbolt cable can transmit only as fast as the thunderbolt port.

If I were to transmit an m.2 signal to a mPCIe adapter to a m.2 receptor, would the mPCIe bus be saturated by the m.2 data?

 

[cub_fanatic]

It is the interface. It is basically like a PCIe 1.0/1.1 x1 slot on a PC. You are getting a single 1st generation lane of PCIe on a mPCIe slot if it is onlu 2.5 GT/s.

I don't really understand what you mean by interface. The example I was trying to understand this from was that a thunderbolt cable can transmit only as fast as the thunderbolt port.

If I were to transmit an m.2 signal to a mPCIe adapter to a m.2 receptor, would the mPCIe bus be saturated by the m.2 data?

The thunderbolt port actually uses some of the PCIe lanes and that is what limits it. The PCIe controller is built into the CPU typically. Most modern consumer level CPUs have 16x PCIe 3.0 lanes natively which is shared by the PCIe slots, mPCIe slots and Thunderbolt ports if the motherboard or laptop has them. There is no separate mPCIe bus. The "interface" I mentioned is the thing with the gold teeth that you plug the expansion card or wifi adapter into. It is the little socket or slot. That slot only has a physical connection to a single PCIe lane which is what is limiting it. The only way to increase its bandwidth is to add more physical connections to the PCIe controller which is part of the CPU's chipset. The reason why Thunderbolt 1 is faster than Thunderbolt 2 is because it uses PCIe 3.0 lanes instead of PCIe 2.0. Each PCIe 3.0 lane has twice the bandwidth as each 2.0 lane so it is theoretically twice as fast which makes TB2 theoretically twice as fast as TB1.

M.2 uses either x2 or x4 PCIe lanes. But, if you use some kind of an adapter to run it through a mPCIe interface, it will only run at x1. So, yes, your M.2 device will completely saturate the mPCIe interface. You might as well just buy a cheaper mPCIe drive with the same capacity instead.