Anyone know what the HT width does?

[JC316]

My mobo has an option called HT Width. It has 16 up and 16 down, 8 up 16 down, 16 up and 8 down, and 8 up 8 down. Does anyone know what the hell it is and what it does?

 

[largon]

HyperTransport bus width

HTT bus is a bidirectional bus. Current A64s support bus width of 16bit both ways.

16 bits x 1000MHz = 16 000 000 000 bit/s = 2000MB/s

Halving the bus width to 8bits (1000MB/s in/out) effectively halves the throughput, thus theoretically decreases the bandwidth board's MCP (southbridge) can offer to addon cards and integrated devices, meaning HDD, PCI, PCIe, etc.

BUT because HTT bus is already such a fast I/O bus, it's not likely even halving the width would make noticeable performance hit. Much like setting HTT multiplier from 5x (1GHz) to 1x (200MHz) does very little in terms of GFX performance.

 

[oily_17]

HyperTransport bus width

HTT bus is a bidirectional bus. Current A64s support bus width of 16bit both ways.

16 bits x 1000MHz = 16 000 000 bit/s = 2000MB/s

Halving the bus width to 8bits (1000MB/s in/out) effectively halves the throughput, thus theoretically decreases the bandwidth board's MCP (southbridge) can offer to addon cards and integrated devices, meaning HDD, PCI, PCIe, etc.

BUT because HTT bus is already such a fast I/O bus, it's not likely even halving the width would make noticeable performance hit. Much like setting HTT multiplier from 5x (1GHz) to 1x (200MHz) does very little in terms of GFX performance.

True,lowering it seems to have no effect on preformance in fact can help when overclocking as trying to run HyperTransport beyond 1Ghz can make system unstable.

 

[JC316]

OK, I see, so there is really no reason to lower it when overclocking since I have lowered the HTT bus anyway. Thanks for the explanation.