* One 16-bit link at up to 5600MT/s
* Up to 8.0GB/s HyperTransport I/O bandwidth; Up to 16GB/s in HyperTransport Generation 3.0 mode
* Up to 37GB/s total delivered processor-to-system bandwidth (HyperTransport bus + memory bus)
Note that the FX supports DDR3-1866 and the page does confirm that total RAM bandwidth is 29.6GB/sec., which is correct. But it also says on the third bullet point above that there's up to 37GB/s worth of off-chip bandwidth, so it means there's around 7.4GB/s worth of HT bandwidth, because DDR3-1866 serves up the remaining 29.6GB/s. If you look at the second bullet point, however, it says there's 8.0GB/s of HT bandwidth, or 16GB/s if you're running in HT3.0 mode. Huh? Aren't these chips supposed to run at the highest HT speeds they can muster and using HT 3.0 when used with a respectable AM3+ motherboard with HT 3.0 support? The first bullet point also says '5600MT/s'. Now how do they do the math? 5600 x 16-bit means there's 11.2GB/s of HT bandwidth, am I correct? Or if we go with the 2 x 16-bit 5600MT/s numbers, there should be 22.4GB/s worth of HT bandwidth, for a total of 52.3GB/s off-chip bandwidth (HT+DDR3). But this is probably wrong.
So, the first bullet point implies 11.2GB/s, the second bullet point says it's either 8.0GB/s or 16GB/s, and the third bullet point suggests that it's 7.4GB/s. WTH, AMD.
Now I'm aware that HT is a packet-based protocol and the data is padded with all sorts of things for control, etc., but Wikipedia also says
With the advent of version 3.1, using full 32-bit links and utilizing the full HyperTransport 3.1 specification's operating frequency, the theoretical transfer rate is 25.6 GB/s (3.2 GHz × 2 transfers per clock cycle × 32 bits per link) per direction, or 51.2 GB/s aggregated throughput
The math is simple enough. If we follow Wikipedia's guidance it means 5600MT/s and a 16-bit (2 x 8-bit) link means 11.2GB/s, aggregate, since I'm assuming the 16-bit HT link includes both up- and down-stream. But is it really just 2 x 8-bit links? I remember my old Athlon 64 X2 PC's BIOS having an option where in you can change the HT link from 2 x 16-bit or 2 x 8-bit. AMD must be nuts to cut HT bandwidth from a 2-CPU to an 8-core CPU.
And as for QPI, Intel practically doesn't even want people to bother with QPI speeds and whatnots. ARK mentions QPI (or DMI) speeds but that's it. No bandwidth claims, just GT/s numbers.