HyperTransport

[Meadows]

I'd like to ask someone professional about the effects of HT speed. Currently I run an Athlon64 X2 processor with an HT speed of 2025 MHz and I'd like to know the job of that link and maybe some performance deltas or stats.

[just brew it!]

In an AMD-based system, HyperTransport is the link from the CPU to the rest of the world, and (in a system with more than one CPU socket) the link between the CPU sockets. All of your I/O goes over HT links.

Except for certain corner cases (e.g. heavily loaded multi-socket servers, high-end SLI rigs) I have a hard time imagining HT being the limiting factor. You're far more likely to be limited by CPU, GPU, or RAM performance.

[Meadows]

All of your I/O goes over HT links.

Do you know of any charts or performance deltas?

[just brew it!]

All of your I/O goes over HT links.

Do you know of any charts or performance deltas?

Not off the top of my head.

But as I (sort of) hinted at above, the HT link to the northbridge is unlikely to be the limiting factor in system performance, unless you're pushing the envelope.

[crazybus]

The HyperTransport bus speed does significantly impact integrated graphics performance, being the connection between the chipset and system memory, but that's probably not an issue for you.

[Meadows]

The HyperTransport bus speed does significantly impact integrated graphics performance, being the connection between the chipset and system memory, but that's probably not an issue for you.

I see, but I was just looking for information and any bit will help make me comprehend this enigma.

[Flying Fox]

"Deltas" compared to what?

[Meadows]

I don't know, something like OS boot speed difference, gaming differences, multimedia performance differences, with several HT speeds. Someone should test that to satiate my strange curiosity.

[sparkman]

FYI, the HyperTransport link in a modern AMD system is conceptually similar to the FSB (front-side bus) in Intel or older AMD systems. But HyperTransport is more sophisticated and you can have multiple channels I think so different subsystems won't necessarily congest each other unlike a FSB.

From: http://reviews.cnet.com/processors/amd- ... 08353.html a little info about HyperTransport speeds:

"The X4 9850, though, features some more technical improvements over the lower-end models, and not just a faster core clock speed. Like the Phenom 9500 and 9600--and past AMD chip designs as well--the X4 9850 has a built-in memory controller regulating the speed at which data moves between the processor and the system memory. It also relies on the HyperTransport 3.0 standard, which links the processor to the various other components in your system, such as the PCI-Express data path for graphics processing. The memory controller and the HyperTransport clock in the earlier Phenom chips came in at 1.8GHz and 3.6GHz, respectively. The Phenom X4 9850 received boosts to 2.0GHz on the memory controller and on HyperTransport to 4.0GHz."