QPI

luckiejacky

I don't understand how QPI works.
I saw on some reports, that said that the bus speed is only 133MHz (21x to CPU speed)
But QPI is 3.0+ GT/s, but how does it work without frequency?
Thanks

mh使者

原帖由 luckiejacky 於 2008-12-17 18:40 發表
I don't understand how QPI works.
I saw on some reports, that said that the bus speed is only 133MHz (21x to CPU speed)
But QPI is 3.0+ GT/s, but how does it work without frequency?
Thanks

原理同AMD既HT差唔多

luckiejacky

原帖由 mh使者 於 2008-12-17 18:44 發表

原理同AMD既HT差唔多

How does HT work?
Thanks

mh使者

原帖由 luckiejacky 於 2008-12-17 18:45 發表


How does HT work?
Thanks

QPI..........慢慢睇
http://www.hkepc.com/1934/page/6#view

qcmadness

原帖由 luckiejacky 於 2008-12-17 18:40 發表
I don't understand how QPI works.
I saw on some reports, that said that the bus speed is only 133MHz (21x to CPU speed)
But QPI is 3.0+ GT/s, but how does it work without frequency?
Thanks

Packet-like data transmittion

133MHz is only the base clock.

luckiejacky

Correct me if I am wrong
If the base clock is 133MHz
if I have 192-bit triple channel memory access 192x133MHz = 26776436736 Bits/s but this number would be multiplied by 40 channels = 1071057469440 Bits/s
if I have FSB 128-bit dual channel memory access 128x400MHz =   53687091200 Bits/s
But only have 1 channel ....
Forget about the maths.... But does QPI works this way?
Thanks

[ 本帖最後由 luckiejacky 於 2008-12-17 19:22 編輯 ]

qcmadness

原帖由 luckiejacky 於 2008-12-17 19:20 發表
Correct me if I am wrong
If the base clock is 133MHz
if I have 192-bit triple channel memory access 192x133MHz = 26776436736 Bytes/s but this number would be multiplied by 40 channels = 1071057469440  ...

No exactly...

QPI has only 20 (+ ECC) lanes per direction.
But the real frequency of the QPI lane will be 4.8-6.4GHz/s (133 x 36 / 48).

So the real bandwidth:
4.8GHz: 4.8GHz x 20-bit = 12GB/s
6.4GHz: 6.4GHz x 20-bit = 16GB/s

luckiejacky

原帖由 qcmadness 於 2008-12-17 19:25 發表

No exactly...

QPI has only 20 (+ ECC) lanes per direction.
But the real frequency of the QPI lane will be 4.8-6.4GHz/s (133 x 36 / 48).

What does 36/48 mean? Sorry for being so stupid..

[ 本帖最後由 luckiejacky 於 2008-12-17 19:29 編輯 ]

qcmadness

原帖由 luckiejacky 於 2008-12-17 19:28 發表
What does 36/48 mean? Sorry for being so stupid..

The real frequency is determined by base clock and multiplier.

luckiejacky

原帖由 qcmadness 於 2008-12-17 19:31 發表


The real frequency is determined by base clock and multiplier.

The multiplier for 920 is 20x wor... how did you get 133Mhz times 36 and divided by 48 from?
And one more question, how does it compare with FSB1600....
Thanks