Editing HyperTransport (section)

=== Links and rates ===
HyperTransport comes in four versions—1.x, 2.0, 3.0, and 3.1—which run from 200{{nbsp}}[[MHz]] to 3.2&nbsp;GHz. It is also a DDR or "[[double data rate]]" connection, meaning it sends data on both the rising and falling edges of the [[clock signal]]. This allows for a maximum data rate of 6400 MT/s when running at 3.2&nbsp;GHz. The operating frequency is autonegotiated with the motherboard chipset (North Bridge) in current computing.

HyperTransport supports an autonegotiated bit width, ranging from 2 to 32&nbsp;bits per link; there are two unidirectional links per HyperTransport bus.  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&nbsp;[[Gigabyte|GB]]/s (3.2&nbsp;GHz × 2 transfers per clock cycle × 32&nbsp;bits per link) per direction, or 51.2&nbsp;GB/s aggregated throughput, making it faster than most existing bus standard for PC workstations and servers as well as making it faster than most bus standards for high-performance computing and networking.

Links of various widths can be mixed together in a single system configuration as in one [[16-bit]] link to another CPU and one [[8-bit]] link to a peripheral device, which allows for a wider interconnect between [[CPU]]s, and a lower bandwidth interconnect to [[peripheral]]s as appropriate. It also supports link splitting, where a single 16-bit link can be divided into two 8-bit links.  The technology also typically has lower latency than other solutions due to its lower overhead.

Electrically, HyperTransport is similar to [[low-voltage differential signaling]] (LVDS) operating at 1.2&nbsp;V.<ref>{{Cite web |title=Overview |url=http://www.hypertransport.org/docs/wp/HT_Overview.pdf |website=HyperTransport Consortium |url-status=dead |archive-url=https://web.archive.org/web/20110716171022/http://www.hypertransport.org/docs/wp/HT_Overview.pdf |archive-date=July 16, 2011}}</ref> HyperTransport 2.0 added post-cursor transmitter [[deemphasis]].  HyperTransport 3.0 added scrambling and receiver phase alignment as well as optional transmitter precursor deemphasis.