[conspire] RAM upgrade -- mix with different CAS Latency?

Edmund J. Biow biow at sbcglobal.net
Thu Nov 16 13:35:53 PST 2006

> Message: 1
> Date: Wed, 15 Nov 2006 17:06:29 -0800
> From: Bill Moseley <moseley at hank.org>
> Subject: [conspire] RAM upgrade -- mix with different CAS Latency?
> To: conspire at linuxmafia.com
> Message-ID: <20061116010629.GA17830 at hank.org>
> Content-Type: text/plain; charset=us-ascii
> I've got a machine with 512MB of PC2700 in a Asus P4PE board.  It's a
> Kingston "ValueRam" KVR333x64c25/512 memory module.
> I'm not clear what I can mix with it.  Does it have to be PC2700, or
> could I use PC3200, for example.  And can memory in the same machine
> have mixed CAS Latency installed?

Yes, you can mix CAS latencies, but the machine will use the highest CAS
latency of the installed chips.  Sometimes you can set the CAS latency
in the BIOS and push up the latency a bit above the one set by the spd
eeprom claims the chip is rated.  With CAS lower is higher, i.e. CAS 2
is faster than CAS 3.  The difference in real world performance I've
found is minuscule, so I don't see the point in messing with the rated
speed.  Also, in my experience, you can use PC3200 with a PC2700 machine. 

Memory compatibility was much more of an issue with 168 pin SDRAM
(PC100-PC133) than 184 pin DDR.  Intel was always much more picky than
Via or SiS, requiring more expensive low density RAM (and sometimes only
seeing half the available memory in high density was used).  If you go
to http://www.pricewatch.com/memory/ and look at specific memory
categories you will see that with the cheaper SDRAM sometimes the
dealers will specify the chipsets with which the memory is compatible. 

Some of the memory dealers have little "memory finders"  on their  web

I've had good luck with 18004memory; here is the page for your  board:

A 512 MB PC2700 CL2.5 (CAS) stick would be about $55, significantly less
than CDW, and not much more than the $47 for the cheapest Pricewatch
generic from the sleaziest vendor. 
> For example could I combine with:
> 512MB DDR DIMM 184-pin 400MHz PC3200
> MFG#: KVR400X64C3A/512
> Which has a CAS of 3.
> Just looking at CDW as an example, it looks like the PC3200 is less
> money than the PC2700 in many cases.
> http://www.cdw.com/shop/search/results.aspx?key=valueram&sr=1&platform=all&x=0&y=0
> Poor machine has a fan going out in it's power supply, too.  It's got an
> Antec SP-350, which I have in a few machines.  First problem with that
> supply.
Speaking of sleazy vendors & power supplies, I always tried to pick a
good "brand name" power supply, even when I tried to shave a few shekels
off the price of some other components.  I used to get what I thought
were a good deal, SPI-Powerman-Sparkle power supplies from a seller at
the old Robert Austin Computer Shows.  A 300 watt PSU would run me under
$30.  I'm guessing the bastards sold me a bunch of refurbs which some
more honest folks sold for $5.  They'd work for a while, but they have
almost all died over time.  Grrrr.


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