HTX Frequently Asked Questions

General Questions

1. What is HTX connectivity?
2. How is HTX connectivity specified and defined?
3. Who can adopt and market the HTX standard?
4. When is HTX needed?
5. What are the advantages of HTX over generic peripheral interconnect standards?
6. Does HTX replace generic peripheral interconnect standards?
7. What are the target markets for HTX?
8. What applications are best suited to leverage the HTX performance edge?
9. What system products can best benefit from HTX-class peripherals?

Business Questions

10. What business value does HTX bring to system/motherboard manufacturers?
11. What business value does HTX bring to subsystem manufacturers?
12. What business values does HTX offer to both system and subsystem manufacturers?
13. Should the industry expect HTX subsystems to be marketed through retail and distribution channels?

Technical Questions

14. How many HTX connectors per system should there be?
15. Would the use of the same mechanical connector for HTX and PCI Express within the same system
      create possibilities of product misplacement?
16. What are the installation options for HTX connectors?
17. Is there a recommended location for the HTX connector?
18. Does the HTX specification define peripheral board dimensions?

Answers to HTX Frequently Asked Questions

1. What is HTX connectivity?

HTX is an innovative, HyperTransport-based, slot-type, direct-connect interface between system processors and peripheral subsystems that:

• Offers the lowest latency and highest performance than any other slot-type interconnect standard
• Empowers a new generation of more integrated, lower cost, function-optimized high-performance systems and peripherals
• Opens the door to innovative high-performance market opportunities to system and peripheral manufacturers, leading to product differentiation and market leadership

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2. How is HTX specified and defined?

HTX is a specification standardized and managed by the HyperTransport Consortium.  The HTX standard specifies the use of 1x and 16x industry-standard connectors that carry HyperTransport-specific signals.  The specification defines electrical features, mechanical features, routing rules, systems design options and signal integrity guidelines of a HyperTransport technology-based motherboard slot connector for board-level subsystems and companion riser cards.

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3. Who can adopt and market the HTX standard?

Any company that is an official member of the HyperTransport Technology Consortium and that, as such, has commercial royalty-free license to HyperTransport technology and the HyperTransport trademarks. Companies can become members of the Consortium by entering into a Consortium membership agreement and by paying a minimal yearly membership fee.   No royalties of any kind are charged to member companies.  For more information on how to become a member, please visit our Membership  section of the web site.

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4. When is HTX needed?

Compute-intensive applications such as algorithm acceleration, security and media processing, CPU/memory scalability platforms, network and cluster interfacing that create an ever increasing demand for interconnect solutions with extremely low latency combined with high bandwidth. HTX can be compared to a car pool lane, providing the fastest way to a destination – i.e. lowest latency - when traffic demand is high.

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5. What advantages does HTX offer compared to generic peripheral interconnect standards?

HTX is the only standardized method to directly connect peripheral subsystems to system CPU without the performance penalty, extra power consumption, and cost burden of intermediate control/interface logic required by conventional I/O interfaces such as PCI Express. The HTX standard delivers:

• Industry's' lowest operational latency and highest bandwidth between CPU and board-level, high-performance subsystems
• Ability to implement in 4-layer motherboards and HTX daughtercards using conventional PCB materials and technology
• Most cost-effective way to deliver highest subsystem performance
• Performance edge required for product differentiation and market competitiveness

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6. Does HTX replace generic peripheral interconnect standards?

HTX targets low latency, compute-intensive subsystem product applications – e.g. algorithm acceleration, security, encryption/decryption and media processing, CPU/memory scalability, networking and clustering – rather than general-purpose, end-user type peripheral applications already egregiously served by other interconnect standards like PCI-X or PCI Express. HTX is not meant to replace but rather complement the above peripheral I/O interconnect standards by delivering the performance edge that they cannot deliver. HTX connectors are typically co-reside with PCI-X and/or PCI Express connectors on the same system board.

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7. What are the target markets for HTX?

HTX primarily targets compute-intensive market sectors such as data centers, high performance computing (HPC), media processing, scientific, military and medical.

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8. What applications are best suited to leverage the HTX performance edge?

• Math and algorithms acceleration
• Server clustering interconnect
• Data security processing  
• Real-time data analysis and routing
• Storage processing 
• Encryption/decryption
• Media encoding/decoding
• Advanced 3D imaging – e.g. entertainment, industrial, scientific, medical
• Other next-generation compute-intensive co-processing functions

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9. What system products can best benefit from HTX-class peripherals?

• Servers
• Blade systems
• Scientific workstations
• Embedded platforms (networking, medical, military, etc.)
• Gaming platforms
• Storage systems

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Business Questions:

10.  What business value does HTX offer to system/motherboard manufacturers?

The opportunity to:

• Tap the performance potential of HTX with very low BOM cost
• Develop universal motherboard platforms for multiple target markets – i.e. through the addition of an HTX connector, manufacturers can design motherboards that are equally suitable for both conventional and high-performance computing markets
• Minimize system manufacturer’s product inventory, stocking and product support costs, as well as maximize product lifespan by leveraging universal motherboard platforms
• Expand pre-sale product configuration and personalization flexibility
• Bring high-performance upgradeability to end-user level
• Become best-in-class suppliers, taking advantage of the commoditization trend that has been sweeping the high-performance computing market

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11.  What business value does HTX offer to subsystem manufacturers?

The opportunity to:

• Deliver state-of-the-art subsystems to multiple system platforms with performance capability unachievable with other interconnect technologies
• Design add-on subsystems that perform at the same peak level of fully integrated system solutions
• Extend own market opportunity by enabling the migration of compute intensive functions from external, closed box and costly platforms to cost-effective, off-the-shelf and fully integrated solutions – e.g. porting of media processing, security processing, data analysis engines, etc. from dedicated network security appliances to data-center servers

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12.  What business values does HTX offer to both system and subsystem manufacturers?

The ability to:

• Participate to higher-end, higher margin markets
• Gain an edge on competition

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13.  Should the industry expect HTX subsystems to be marketed through retail and distribution channels?

In view of the high-end markets that HTX products serve, HTX-based peripherals require professional installation and configuration.  Therefore, unlike PCI-class products, they are sold and supported by Original Equipment Manufacturers (OEMs) or by Value Added Resellers (VARs).

Unlike PCI-class interconnects, HTX does not cater to the end-user market and therefore HTX peripherals are not usually sold through distribution or retail channels.

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14. How many HTX connectors per system should there be?

There can be as many HTX connector slots as there are CPU-native HyperTransport links available in the system. One or two HTX connector per system/motherboard is considered adequate for current HTX designs.

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15. Would the use of the same mechanical connector for HTX and PCI Express within the same system create possibilities of product misplacement?

In accordance with the HTX specification, HTX connectors are to be reverse-installed (rotated 180 degree) in respect to conventional PCI Express connectors, thereby preventing any possibility of HTX or PCIe boards misplacement

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16. What are the installation options for HTX connectors?

HTX connectors can be installed:

• Directly on the system motherboard – such as alongside conventional PCI-class connectors - for vertically-mounted HTX boards in 3U or higher profile server chassis
• On an HTX specification-defined riser card to allow the use of a horizontally-installed, full-sized HTX board  in a 1U rack-type chassis
• On a proprietary riser card defined by the system manufacturer

By using different versions of riser cards and with each supporting a different type of slot interconnect standard (HTX, PCI Express, PCI-X, etc.), system manufacturers can leverage a single motherboard design to deliver easily configurable, cost-optimized, application-specific system configurations.  Installation options can extend to any variation that system manufacturers see fit for their own market and customer base.

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17. Is there a recommended location for the HTX connector?

For a standard EATX motherboard design, the HTX specification recommends slot 6 for the following reasons:

• It is the most easily routable location
• It has the shortest and most direct path for HyperTransport signals
• It can host HTX boards with the same full-size form factor as PCI in a 1U system chassis (by means of a riser card)

System manufacturers may choose locations other than slot 6 for the HTX connector that they may deem more suitable for specific market targets and applications, provided they are in compliance with proper routing and signal integrity guidelines.

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18. Does the HTX specification define peripheral board dimensions?

Yes. Low profile cards are also supported provided that the proper mechanical integrity, support and retention are maintained. The HTX specification defines peripheral boards that are mechanically compatible with the PCI standard and that fit in conventional chassis designs.

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