NF 4 & HyperTransport & PCI Express + 3 GB SATA = Bottleneck?

[RyanLM]

I am trying to understand how this all fits together. My confusion is this, looking at the Chip Layout of the NF4 found here: http://www.tomshardware.com/mo...041020/nforce4-01.html (only place I found it) it shows that the HT link between the MCP and the CPU is 1 GB/Sec. However, PCI Express alone could flood that out, let alone the new SATA revision - but then I look on NVIDIAs site any they say its 8 GB/Sec. My first guess is that they mean Gigabit, not byte, but it is a Capital B on there:

An extremely fast dedicated HyperTransport link lets the NVIDIA MCPs communicate with the CPU at up to 8.0GB/sec., which ensures ample system bandwidth

http://www.nvidia.com/object/feature_single-chip.html

Now granted it say Up to, but what is that what it is? Is it a 1 GB/sec connection to the CPU or is it an 8GB one?

Thanks.

 

[Concillian]

HT is 6.4 GB/sec at 800 MHz
http://www.tomshardware.com/cp...030422/opteron-06.html

16 bit * 800MHz * 2 (DDR) / 8 bits per byte = 3.2 GB/sec in each direction

1000 MHz HT will be 4GB/sec each direction, which is where they're getting that 8GB/sec figure (4GB/sec x 2 directions)

I'm 99% certain that the other Tom's article means 1GHz not 1 GB/sec

And the thing about 3Gb (bit not byte) SATA is funny because you get dedicated bandwidth to each drive, but there aren't even drives capable of sustained read or writes even that close to 1 Gb/sec. 3Gb/sec is just silly. But it's good to have overhead I guess.

 

[RyanLM]

See, not that makes sense. The thing that does bug me is it really looks like an nVidia graphic that says 1 GB. But, it cant mean that.

The SATA 3Gb thing is actually cool because you can use a multipler now to hook more than one drive to it.

Thanks for the input!

 

[CMbit]

Yes, overhead is good. It seems that no matter what speed a device 'operates' at, is no where near the speed that it actually 'performs' at.

an example...

I have DSL Lite (128 kbps). The fastest rate in which I have ever seen a download was probably around 30 kbps. It is probably the same w/ Hard Drives, 1394 devices, USB2.0 devices, so on and so forth....