Trey Holm's post:-

<<<< I am not sure.  It came with four RAM slots, all filled with 512's.
After about a year I replaced two of the sticks with 1G sticks.  Windows
picked these up without a problem. Six months later, the present day, I
replaced the second set.  However, this time the new sticks were not
picked up.  The configuration of the sticks before this last upgrade
was:  512-1G-512-1G.  Now, the BIOS shows: 1G-1G-1G-1G, but Windows says
3024 KB.>>>>

Hi,

the memory modules "DDR2 memory modules should be installed in pairs of matched memory size, speed, and technology"

this is what the manual for dimension 4700 says. pl. go to the following URL, download the pdf format " contents: dell dimension 4700" and from page 57 onwards there are detailed instructions on memory upgrades

  http://tinyurl.com/zonb3


for your ready ref. i am copy/pasting a portion of it

  <<<< Memory
You can increase your computer memory by installing memory modules on the system board.
Your Dell Dimension™ computer supports DDR2 memory. For additional information on the type
of memory supported by your computer, see "Memory" on page 91.
DDR Memory Overview
DDR2 memory modules should be installed in pairs of matched memory size, speed, and technology.
If the DDR2 memory modules are not installed in matched pairs, the computer will continue to
operate, but with a slight reduction in performance. See the label on the upper-right corner of the
module to determine the module’s capacity.
NOTE: Always install DDR2 memory modules in the order indicated on the system board.
The recommended memory configurations are:
– A memory module installed in connector DIMM connector 1
or
– A pair of matched memory modules installed in DIMM connectors 1 and 2
or
– A pair of matched memory modules installed in DIMM connectors 1 and 2 and another
matched pair installed in DIMM connectors 3 and 4
NOTICE: Do not install ECC memory modules.
• If you install mixed pairs of DDR2 400- and 533-MHz the modules function at the slowest
speed installed.
• Be sure to install a single memory module in DIMM connector 1, the connector closest to the
processor, before you install modules in the other connectors.
58 Removing and Installing Parts
www. d e l l . c o m | s u p p o r t . d e l l . c o m
NOTE: Memory purchased from Dell is covered under your computer warranty.
NOTICE: If you remove your original memory modules from the computer during a memory upgrade,
keep them separate from any new modules that you may have, even if you purchased the new modules
from Dell. If possible, do not pair an original memory module with a new memory module. Otherwise, your
computer may not start properly. You should install your original memory modules in pairs either in DIMM
connectors 1 and 2 or DIMM connectors 3 and 4.
Addressing Memory With 4-GB Configurations
Your computer supports a maximum of 4 GB of memory when you use four 1-GB DIMMs. Current
operating systems, such as Microsoft® Windows® XP, can only use a maximum of 4 GB of address
space; however, the amount of memory available to the operating system is less than 4 GB. Certain
components within the computer require address space in the 4-GB range. Any address space
reserved for these components cannot be used by computer memory.
Installing Memory
CAUTION: Before you begin any of the procedures in this section, follow the safety instructions
located in the Product Information Guide.
NOTICE: To prevent static damage to components inside your computer, discharge static electricity
from your body before you touch any of your computer’s electronic components. You can do so by
touching an unpainted metal surface on the computer chassis.
1 Follow the procedures in "Before You Begin" on page 47.
2 Lay the computer on its side so that the system board is on the bottom of the inside of the
computer.
matched pair of memory modules in
DIMM connectors 1 and 2 (white
securing clips)
matched pair of memory modules
in DIMM connectors 3 and 4
(black securing clips)
Removing and Installing Parts 59
3 Press out the securing clip at each end of the memory module connector.
4 Align the notch on the bottom of the module with the crossbar in the connector.
NOTICE: To avoid damage to the memory module, press the module straight down into the connector
while you apply equal force to each end of the module.
5 Insert the module into the connector until the module snaps into position.
If you insert the module correctly, the securing clips snap into the cutouts at each end of the
module.>>>>.

BTW your model supports MAX 4 gig memory.

good luck----Venkat

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