[SI-LIST] Re: CPU/Memory/Buss Speed ?
- From: "Steven M. Waldstein" <swldstn@xxxxxxxxxxxx>
- To: <Pat_Diao@xxxxxxxx>, <si-list@xxxxxxxxxxxxx>
- Date: Fri, 5 Mar 2004 19:03:24 -0500
Pat,
Lets start with a current PC.
The Intel Pentium 4 to Memory Host Bridge (MHB) interface
runs at 800 MHz and uses AGTL+ it is a 64 bit wide bus
so it translates to 6400 MBytes/s.
That is why you will see the 875 MHB with two DDR400 memory
buses, each 64 bits wide. This also is running at 3200 MBytes/s
per channel. The base clock for this DDR system has a
5 ns cycle time.
AGP uses a 66MHz base clock but runs date at 1X, 2X, 4X or 8X.
The bus is 32 bits wide so you end up with up to 2112 MBytes/sec
of throughput.
PCI buses run up to 66 MHz and 64 bits wide for 533 MBytes/sec
PCI-X buses run up to 133 MHz and 64 bits wide for 1066 MBytes/sec
Each of these can also be built at 32 bits which is more common
in current desktop PC.
PCI-Express is 2.5 Gbits/sec/lane. Once you take off the overhead
of the 8bit/10bit encoding you end up with 238 MBytes/sec/lane.
You will see 1,2,4,8,16 and 32 lane implementations eventually.
The AGP replacement will be 8 lanes I think.
All of these are raw data speeds that will never be realized but
is a good point of comparison.
Hope this is the kind of info you were looking for.
Steve
swldstn@xxxxxxxxxxxx
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx
[mailto:si-list-bounce@xxxxxxxxxxxxx]On Behalf Of Pat Diao
Sent: Thursday, March 04, 2004 8:42 PM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] CPU/Memory/Buss Speed ?
The question came out from a discussion:
Can anyone give a clear idea of the speed parameters used in PC, which
includs Buss speed, Memory access speed, Harddisk data speed? What are the
typical values in the latest PCs?
What is the relation between ns (memory access) and Mb/s? In terms of SI
evaluation, are any of these speeds "beefed" up for commercial reasons?
Thanks
Pat
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