"Lanning" wrote in message
...

"LVTravel" wrote in message
...


"Lanning" wrote in message
...
You make a great point! Thank you very much. If I stick to the manual's
recommendation of set(s) of four matched modules, then I should put a
new
set of four matched 1GB (rather than 512MB) sticks in the front set of
four
slots.

Would there then be any issue if I also put the current four matched
512MB
sticks in the back set of four slots?

As you surmise, the manual says, "This computer supports a maximum of 32
GB
of memory when eight 4-GB DIMMs are installed."

"LVTravel" wrote in message
...


"Lanning" wrote in message
...
The 490 manual states, "For optimal performance, fully buffered DIMMs
(FBDs) should be installed in *matched sets of four*. This enables
quad-channel operation and provides the highest memory bandwidth.
Fully buffered DDR2 memory modules can also be installed in pairs of
two; in this case, the computer will continue to operate, but with a
*slight reduction in performance*."

Please comment on the *"slight reduction in performance"* that I
should expect when adding two 1GB modules rather than four 512MB
modules to the existing four 512MB modules.

I have already ordered two 1GB modules from Crucial, but I could
return them box unopened and spend $50 more to get four 512MB modules
if it matters. Of course, I should have read the manual and posted
this question before ordering the memory.

Thanks for any advice and information.

Roy


So, you are upgrading from 2 GB of memory to 4 GB. Does your computer
have 4 open memory slots? Unless you do, you would need 4 1 GB modules
and remove the 4 512 MB modules you now have installed.

If this is the Dell Presicion 490 board I would recommend that you
purchase 4 1 GB cards which should run you about 159.96 which is only
$30 more than 4 512 MB modules.


http://www.crucial.com/store/listpar...kStation%20490
Part Description Price ea. Qty Total
CT675884 1GB, 240-pin DIMM $ 39.99 X 4 $ 159.96

This way, if you decided to increase to 8 GB or larger later for 64 bit
OS, you would remove the 4 512 modules you now have and upgrade them to
1 or 2 GB cards. That motherboard apparently can handle 8 4GB memory
cards for 32 GB of RAM.


You should have no issues anyway but I would recommend that you move the
4 512MB sticks to the currently vacant slots and putting the 4 1GB sticks
in the original slots. It shouldn't really matter for speed if you just
put the new chips in the vacant slots but some computers just seem to run
better with the larger chips in the bank 0 slots (or at least that is the
way it used to be and of course that is IMHO.)

I put the two 1GB sticks in the first two slots of the second set of four
slots. It's all dual-channel, now. Says so in CMOS. I'll live with it.

Here's something someone quoted about *equal capacity* that I believe:

"Additional non-shipping (but valid) configurations can be made by
installing matched pairs of DIMMs in slots DIMM1/DIMM2, DIMM3/DIMM4,
DIMM5/DIMM6, and DIMM7/DIMM8. These will result in dual channel operation
which is lower bandwidth that quad-channel (where DIMM1/2/3/4 and
DIMM5/6/7/8 are required to match for full quad-channel). We do not ship
these configurations, but they are valid and no error message will be
displayed."

-----------------------------------------------------------------------------

MSINFO32.EXE now reports memory as (in Vista Business SP1):

installed was 2.00 GB, now 4.00

total physical was 2.00 GB, now 3.25

available physical was 879 MB, now 2.36 GB

total virtual was 4.23 GB, now 6.71

available virtual was 2.69 GB, now 5.79

page file was 2.29 GB, now 3.54


The only reason I was trying to get you to go with the 4 1GB chips instead
of just two was the issue with chip matching. I at that time didn't realize
that you were using a 32 bit operating system (OS.) If you later purchase 2
1GB chips, even from the same manufacturer, they may not match and therefore
won't work correctly. It does look like you are only using a 32 bit OS so
the additional memory right now would not have been helpful. Only if you
went to the 64 bit version of the OS.