2 ghz system bus ? 8/14.4gb? how is this calculated ? help on amd architecture plz

[mikedev10]

hey guys - looking for an in depth explanation of amd architecture and how what exactly is going 2 ghz. and how the bandwidth below is determined.

basically how they get these numbers, for dual channel ddr 400 ram.

http://www.amd.com/us-en/Processors/Pro...ion/0,,30_118_9485_13041^13043,00.html
HyperTransport? technology for high speed I/O communication
One 16-bit link at 2000MHz
8 GB/s HyperTransport? technology I/O bandwidth
14.4 GB/s total delivered processor-to-system bandwidth



here are my numbers, incorrect assumptions yet hopefully correct math:

A:

pc3200 ddr400 3.2gB
pc4000 ddr500 4.0gB

100 mhz ddr = .8gB of memory bandwidth

200 million cycles = .8gB

200000000 cycles = 6710886.4 bits (.8 * 8 * 2^(10*2))

1 cycle = 0.033554432 bits transferred

shouldn't this be something like 32 bits transferred per cycle?



B:

One 16-bit link at 2000MHz
8 GB/s HyperTransport? technology I/O bandwidth
14.4 GB/s total delivered processor-to-system bandwidth

100mhz ddr = .8gB
1000mhz ddr = 2000mhz = (10*100mhz) ddr = 8gB - from hypertransport - what exactly is this, what is this connecting? seems to have nothing to do with the memory bus;

14.4gB - 8gB = 6.4gB;

two channels for memory; 6.4/2 = 3.2gB per channel = bandwidth of pc3200 400mhz ddr ram. so what exactly is this HT area doing?

thanks for any help in my understanding !

 

[hardwareuser]

I think I had the same question as you before.

The hypertransport deals with the I/O devices, not the RAM. The RAM is dealt with by the integrated memory controller.

I hope my answer is right.

 

[mikedev10]

should i really care that my pci bus has 8gb of transfer? what's the deal here? is this purely a benefit of only the video card?


still interested in how my math is messed up in the first question.

 

[hardwareuser]

They say "14.4 GB/s total delivered processor-to-SYSTEM bandwidth", so that's just as you calculated on part B. As to why they put that under hypertransport, I dunno. It's probably just to add some impressive numbers.

I'm not sure how much the added bandwidth helps since I don't know how much video cards use up. It should help, especially if you're using several of them at the same time (like HD + video card + sound card). I'm sure you've had experiences where your entire computer slowed down a lot when it was accessing the HD (and not just due to the processor waiting for data from the HD). With the separated memory bus and hypertransport bus, this shouldn't be a problem anymore anyway.

Sorry, my answers are all really "theoretical" and not very solid