CAS latency really that important?

is CAS latency really that important? i see very expensive modules out there
with a cas 3 latency, and less expensive ones with a cas 2 latency. so i'm a
bit confused.

It's only worth a few % in performance.


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Here's the article.

http://www.tomshardware.com/2004/01/19/ups_and_downs/


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Yipes, I found another article that shows more differences.

http://www.anandtech.com/memory/showdoc.aspx?i=2392&p=1


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In article , Spaceman
says...
is CAS latency really that important?

Absolutely.

i see very expensive modules out there
with a cas 3 latency, and less expensive ones with a cas 2 latency. so i'm a
bit confused.

CAS3 is slow, CAS2 is faster. You want as lower figure as possible.

--
Conor,

Same ****, different day.

Conor wrote:
In article , Spaceman
says...
is CAS latency really that important?

Absolutely.

i see very expensive modules out there
with a cas 3 latency, and less expensive ones with a cas 2 latency. so i'm a
bit confused.

CAS3 is slow, CAS2 is faster. You want as lower figure as possible.


****ing idiot

"rex roland" wrote in message . ..
Conor wrote:
In article , Spaceman
says...
is CAS latency really that important?

Absolutely.

i see very expensive modules out there
with a cas 3 latency, and less expensive ones with a cas 2 latency. so i'm a
bit confused.

CAS3 is slow, CAS2 is faster. You want as lower figure as possible.


****ing idiot

Bingo.

'Spaceman' wrote:
| is CAS latency really that important? i see very expensive modules out
there
| with a cas 3 latency, and less expensive ones with a cas 2 latency. so i'm
a
| bit confused.
_____

You seem to have CAS 3 latency and CAS 2 latency reversed. CAS 3 latency is
cheaper and slower than CAS 2 memory. Any price difference that makes CAS 2
memory cheaper than CAS 3 memory must be based on some other factor.

As for the EFFECT of CAS 3 and CAS 2; it depends.

1. CAS latency only comes into play when the initial address is sent out to
memory. For sequential fetches that follow, CAS latency plays no part.
2. If the data or instructions needed are already in the L1 cache or L2
cache, main memory CAS latency plays no part at all. Because data and
instructions tend to be localized in time and space (recently used or in
nearby locations) caches can greatly reduce the affect caused by main memory
being clocked and such a much lower rate than CPUs. This is a complex
dependency and varies according to the type of application, the techniques
used in programming, compiler functions, and CPU design. As a rule of thumb
a 2 way associative 16 KByte L1 data cache the next data needed will likely
be in the L1 cache (requiring no access to main memory) 95% of the time.
Similarly, a 2 way associative 512 KByte L2 data cache will have the next
data needed almost 99.5% of the time (requiring no access to main memory.)

The result is that the difference in performance for a program that fits all
data and instructions into L1 and L2 caches is almost zero between a system
equipped with CAS 3 versus CAS 2 main memory.



You can check the effect of cache performance vs. memory performance using
the comparisons in SiSoft Sandra 2004.

Phil Weldon

"Spaceman" wrote in message
...
| is CAS latency really that important? i see very expensive modules out
there
| with a cas 3 latency, and less expensive ones with a cas 2 latency. so i'm
a
| bit confused.
|
|

"rex roland" said: "****ing idiot" in response to the
imbecilic posting:
CAS3 is slow, CAS2 is faster. You want as lower figure as possible.
Conor

Give him a break. Even ****ing idiots do something right once in a long
while (although I can't imagine what it could be)...

"Bob Doran" wrote in message
...
"rex roland" said: "****ing idiot" in response to the
imbecilic posting:
CAS3 is slow, CAS2 is faster. You want as lower figure as possible.
Conor

Give him a break. Even ****ing idiots do something right once in a long
while (although I can't imagine what it could be)...

Pathetic ranting.

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Ed Light

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