HyperTransport Bandwith...

[harl]

I'm a bit confused about Hyper transport
bandwith.

It's
1 GHz * 2 Bytes = 2 GB/s in each direction ?

Or It's

1 GHz * 2 (DDR) * 2 Bytes = 4 GB/s in each direction ?

I have read lot's of versions and I I'm more confused ...