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Subject: Re: SURPRISING RESULTS P4 Xeon dual 2.8Ghz

Author: Vincent Diepeveen

Date: 09:35:42 12/17/02

Go up one level in this thread


On December 17, 2002 at 12:14:49, Matt Taylor wrote:

>On December 17, 2002 at 11:30:36, Robert Hyatt wrote:
>
>>On December 17, 2002 at 11:28:27, Matt Taylor wrote:
>>
>>>On December 17, 2002 at 11:20:38, Enrique Irazoqui wrote:
>>>
>>>>Deep Fritz 7 runs about 8% faster on a dual Xeon 2400 (detected as 4 cpus)than
>>>>on a dual AMD MP 2200+ (2x1800 GHz). Both with DDR 333.
>>>>
>>>>Enrique
>>>
>>>Which board/chipset? I haven't seen any SMP boards that support better than a
>>>133 MHz FSB, and it's been a bitter disappointment.
>>>
>>>-Matt
>>
>>
>>hard to compare FSB clock speeds when double-pumping and quad-pumping are thrown
>>in.  I think it stupid of Intel to say "quad-pumped 133" since it really isn't
>>133.  It is
>>4 X 133.
>
>Do that and you get the DDR nonsense. "Oh it's a 333 MHz bus." No. It's a 166
>MHz bus. It smells, looks, tastes, and acts like a 166 MHz bus. It has the
>latency of a 166 MHz bus. It has twice the throughput, but it is still a 166 MHz
>bus. It is DDR, but it is not 333 MHz. I'd imagine you could get rich off of all
>this false advertising.
>
>It is really difficult to define what they mean by "quad-pumped." Whether
>through ignorance or whatnot, I hear people refer to DDR as "double-pumped" and
>RDRAM as "quad-pumped," but RDRAM uses a dual-channel DDR bus. Either I'm
>missing something or the whole idea of "pumped" is ambiguous. Maybe the people I
>talk to are idiots. I don't know.

RDRAM has 15T latency, DDR ram has 11 T latency.
if i remember well CAS2 DDR ram has 10T latency and registered ddr ram
cas 2.5 has 12T latency. I do not know about speeds of ECC registered
RDRAM but it must be a lot worse than 15T latency.

Still a lot of the Xeons are working at quad pumped RDRAM, so that's 100Mhz
even if we jump 100 meters high.

100Mhz and 15T latency is a lot worse than 133Mhz and 10T latency.

Best regards,
Vincent



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