I need to correct my statement after switching chips around again -   If I switch the slots for one chip from slot 0 to slot 1 both channel A, I lose the dual channel, now shows single channel but DDR still =400.  Using slot 0 channel A and slot 1 channel B is the same result.  In all cases, bus speed stays at 400 and system bus speed stays at 800, only dual channel and single channel indicator changes.  
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From: Hachmeyer, Mr. Paul S.
Sent: Thursday, December 04, 2008 3:32 PM
To: Personal Computer Hardware discussion List
Subject: memory chip matching

A few friends are asking me about adding memory to their pc's.  I know that mixing somewhat compatible memory can result in 'slower speeds', but I'm looking for a little clarification of what is 'slower'.  I know if I mixed a pc3200 (multispeed) chip with a pc2700 chip, both would slow to pc2700.
But I have some chips from different manufacturers, all are pc3200U- DDR200 according to a memory spec reader.  But they show different 'set timings' - one has 3.0-3-3-8, the other, 3.0-4-4-8.  My bios says that both are installed in slot 0, one in memory channel A, one in channel B, showing memory mode 'dual channel', and DDR=400.
If I switch the slots for one chip, I lose the DDR=400 and dual channel, shows DDR=200 and single channel.  So the Dual Data Rate is kicking in.  Are the -4-4-8 and -3-3-8 numbers CAS, latency, etc?  How critical are they?  Will they run together without issues?  PC's are used mostly for web surfing, light gaming, email, office functions.
Paul Hachmeyer

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