Re: ram

[Francesco Pietra <frapietra@alice.it>]

Hi Len:
a lucid lesson from you. Thank you
Francesco Pietra

On Friday 07 April 2006 15:05, Lennart Sorensen wrote:
> On Fri, Apr 07, 2006 at 09:02:45AM -0400, Lennart Sorensen wrote:
> > On Fri, Apr 07, 2006 at 06:57:06AM +0200, Francesco Pietra wrote:
> > > In setting up a workstation with
> > >
> > > --two amd6a 265 opterons dual core
> > > --Tyan K8WE S2895SA3NRF main board
> > > --two 360GB raid1 hd (raid 1 software by debian)
> > > --ram 2GB (Kingston KVR400D4R3A/2G - DDR 400 Ecc Registered), is any
> > > reason to prefer two slots of memories 1GB each instead of a single 2GB
> > > slot?
> > >
> > > The technician here maintains that two slots are needed to have needed
> > > two channels.
> > >
> > > Incidentally, the 2GB Kingston is charged in Italy six hundred euros,
> > > that is more than twice the price in US. This is to recognize that we
> > > can circumvent the market leader software houses (and be more
> > > efficient) but we cannot avoid the system in our country which favors
> > > handlers against citizen (and against scientific research activities).
> > > The results of such policy are under the eyes.
> >
> > With 2 * 1GB, you get 6.4GB/s memory bandwidth.  With 1 * 2GB, you get
> > 3.2GB/s memory bandwidth.  I think that is a reason to prefer the
> > pair 1GB sticks
> >
> > Socket 939/940 AMD's have dual channel memory controllers to get double
> > memory bandwidth, but only if you put in at least two sticks of memory
> > (and into the right slots on the board).
>
> Actually since you are using 2 cpus, you really would want at least 4
> sticks of identical memory to get full performance from the system since
> each cpu has a dual channel memory controller.  You need need memory in
> each channel of each cpu if you want the maximum performance.
>
> Len Sorensen