Usb 3.0 19 pin to 20 Pin Compatibility

[ComputerJuice0903]

I'm building my first computer and i was curious about the usb 3.0. my motherboard has a 19 pin header, but my case has a 20 pin connector. I was doing research for an adapter of some sort and came across headers that go into a pci slot. But when i looked at pictures it only had 19 pins even though it was advertised for 20 pins. There's no point because my motherboard has 19 pins. I did research and there isn't much that i found, but some people say you can plug 20 pin into 19 pin headers because the last one is a key pin or something like that. I'm looking for a solid explanation as to why the pci expansion cards are advertised as 20 but only have 19 and also if i can just plug the 20 pin connector into the 19 pin header.

Thanks

 

[legokill101]

basicly you case one had a blocked off pin slot in the conector so that the usb front panel conector will only fit one way preventing you from reversing it

 

[legokill101]

basicly you case one had a blocked off pin slot in the conector so that the usb front panel conector will only fit one way preventing you from reversing it

 

[mauller07]

basically what the guy above mentioned, there is an odd number of pins on the usb 2 and 3 headers and it is normally used as a keying besides the keying on the connector itself.

 

[ComputerJuice0903]

I can see 20 holes for 20 pins so even though it looks like there are twenty holes you're saying one is blocked off. so how do i know which one is blocked off

 

[mauller07]

just dont worry about it, the connector itself should be keyed to only fit one way.