Ed Vance -> Dale Shipp wrote:

 EV>> My HP a1430n XP SP3 pc has a AMD 3800+ Dual Core CPU and has been
 EV>> acting very slow when starting up or when I start a program.

 EV> I couldn't see trashing the two 500MB DDR 400 sticks and buying four 1GB
 EV> sticks to fill all the slots, so I decided 3GB should be enough on a pc
 EV> with a CPU that run at 2 Mc/s.

 EV> The XP OS is 32-Bit and I was told here that the maximum RAM it could use
 EV> was 3.8GB iirc.

 EV> Is that still true?

G'day Ed.   I still settle for XP on a couple of computers here and have 
explored the ram upgrade options as you have.  XP is indeed limited to
about 3GB ram (I have seen people quoting estimates between 3.25 and 3.8)
So, there is no point going beyond the 3gb that you have invested in.

I have also bumped up the ram in one specific HP model (it too just had
2x500mb modules) but the mobo manual indicated that in order to maintain
and activate the fast "Dual channel" processing speeds, the ram
modules had to be in specific slots.

In my case the mobo supported up to 8gb but it only had XP 32-bit
installed, so no point going beyond 3gb. However, to maintain the
dual-channel speeds, the modules had to be "balanced" across the
dimm slots.

Originally, the 2x500mb modules were in slot 1 in each bank. That triggered
the proper dual channel mode.  All I had to do was add each 1GB module
right next to the 500mb module in the same bank to maintain the balance.
The "banks" are often colour-coded to indicate their pairing.
BUT, your mobo might have another design.

I won't go into techy details about all that because your mobo manual could
probably explain it with illustrations for your particular mobo.

Also, the pc will only operate as fast as the slowest supported module. For
example, if the 500mb modules are PC4300 rated, don't expect faster
performance if you add PC6300 modules.

The best performance difference would be to main the
"dual-channel" mode vs "single-channel" mode.

Ciao! ..AA