B
Black Jack
http://www.anandtech.com/news/shownews.html?i=21695
They report that Intel might switchover to a three-chip model (in
contrast to the rest of the industry considering one-chip models to be
the panacea), which would make it a contratrarian move. It's generally
thought that having less chips increases economy.
The three chips of the chipset would be the TNB (RAM-controllerless
northbridge), XNB (RAM controller), and ICH5 (i/o hub southbridge).
The XNB and ICH5 would both hang off of the TNB, and the TNB would
directly connect to the Xeon MP. This roughly seems to mimick AMD's
design, as the TNB would be roughly equivalent to an Opteron
Hypertransport link, while XNB would be roughly an Opteron RAM
controller. But of course this would be all external to the Xeons,
unlike in the Opterons. Also it looks like having the XNB hanging off
of the TNB would make the TNB extremely busy, handling both i/o coming
in from RAM and from peripherals; just like it does these days, so I
don't see where either economy or performance are to be had.
However, I do see that separating out the RAM controller might allow
them to attach multiple RAM controllers in an attempt to mimick the
scaling that multi-Opterons have. However, having the RAM controller
on a separate chip might increase the number of hops between RAM and
CPU, thus increasing latency. So a good solution for RAM bandwidth,
but a bad solution for RAM latency, perhaps?
Yousuf Khan
They report that Intel might switchover to a three-chip model (in
contrast to the rest of the industry considering one-chip models to be
the panacea), which would make it a contratrarian move. It's generally
thought that having less chips increases economy.
The three chips of the chipset would be the TNB (RAM-controllerless
northbridge), XNB (RAM controller), and ICH5 (i/o hub southbridge).
The XNB and ICH5 would both hang off of the TNB, and the TNB would
directly connect to the Xeon MP. This roughly seems to mimick AMD's
design, as the TNB would be roughly equivalent to an Opteron
Hypertransport link, while XNB would be roughly an Opteron RAM
controller. But of course this would be all external to the Xeons,
unlike in the Opterons. Also it looks like having the XNB hanging off
of the TNB would make the TNB extremely busy, handling both i/o coming
in from RAM and from peripherals; just like it does these days, so I
don't see where either economy or performance are to be had.
However, I do see that separating out the RAM controller might allow
them to attach multiple RAM controllers in an attempt to mimick the
scaling that multi-Opterons have. However, having the RAM controller
on a separate chip might increase the number of hops between RAM and
CPU, thus increasing latency. So a good solution for RAM bandwidth,
but a bad solution for RAM latency, perhaps?
Yousuf Khan