I want to upgrae the ram memory on my compaq6720s note book but cant find where to put it i can see the 1 gb of sodium memory but only seems to be the one slot it says there are two slots available but i dont know where the 2nd on is

Maybe 1GB is the maximum amount of memory that your system will hold. And maybe your system likes memory to be in pairs, so when you put the 1GB in by itself it didn't work, but when you put it in with a 512MB it works.

What you need to do is right-click on My Computer > Properties > Advanced tab. Click "Settings," click "Advanced" and under the Virtual Memory heading, click "Change." Click the custom size setting and put the minimum at the same amount of RAM you have (ie 1 gb = 1024, 2 gb = 2048, etc...). Put the maximum at double the amount of RAM you have. This should fix that error.

RAM / Max RAM Up to 1 GB of DDR2 533 MHz memory, upgradeable to
2 GB using two soDIMM modules (dual-channel support) RAM / Max RAM Up to 1 GB of DDR2 533 MHz memory, upgradeable to
2 GB using two soDIMM modules (dual-channel support) RAM / Max RAM Up to 1 GB of DDR2 533 MHz memory, upgradeable to
2 GB using two soDIMM modules (dual-channel support) RAM / Max RAM Up to 1 GB of DDR2 533 MHz memory, upgradeable to
2 GB using two soDIMM modules (dual-channel support)Max RAM: Up to 1 GB of DDR2 533 MHz memory, upgradeable to
2 GB using two soDIMM modules (dual-channel support) This is the kind of memory you need, no matters the branch

You need the EXACT speed rated RAM.
Your support page states it needs.....
400-MHz DDR2 SDRAM
NOTE: Your computer supports only registered memory

Memory capacities
256-MB, 512-MB, 1-GB, 2-GB, and 4-GB ECC

256-MB, 512-MB, 1-GB, 2-GB, and 4-GB ECC modules to a max of 16GB
more info here
http://support.dell.com/support/edocs/systems/ws470/en/ug_en/about.htm

Maximum Total Amount is 1GB.

EACH ram slot's Maximum Amount is 512MB.

Note* If you only install one ram memory module, make sure it goes into Slot 1.

(On the motherboard it may have DIMM 1, printed next to the slot)

Slot one is closest to the Processor. The processor reads ram memory that is in Slot 1, first.

why do you put cash on such an old horse? P4, wow... with a square screen no less.
the PC has book at HP, many , one is service,
and shows all processors offered for the time it was made.
read that yet?
no you cant add more ram.
it also uses ram that is not made now. making this harder, to the max. ask , Frankston memory this question.
for $20 at Goodwill buy one far newer, and avoid this thing,

sorry but that is best, why mess with an old compaq relic MOBO.?
the laptop only runs laptop CPUs.
why do it. name 1 good thing about old laptops?

 you put the 2 gb in the first slot(that's the default setting on all motherboards-the biggest memory is in front) then in the second slot the 1 gb after that restart if you get the same sound the remove the battery on the motherboard and put it back to reset the bios after that restart. 

nope, 1 slot can only accomodate 2gb of ram. and also take NOTE that 4gb can only be read if the windows is running 64bit ,now if the system is running 32bit and there are 4 gb of ram installed on the system . The system will only read 3 or 3.5 gb of ram.

Dear Sir,

You can install upto 3 GB RAM. i.e. 1GB PC3200 DIMM RAM in each slot.

Please go to BIOS settings & load the defaults. / check following. BIOS settings.
DIMM clock & timing is auto/ detected by SPD (Serial Presence Detect)

Possibly the 1GB RAM you are trying to install does not have SPD / is faulty. Try with a new / working 1 GB RAM.

Hope this helps you friend...

I had the same issue on this board where it came with a Samsung 512 MB 533 MHz PC2-4200 DDR2 DIMM. I put in a 1 GB Kingston with the same specs (533 MHz PC2-4200 DDR2) and it would not recongize the Samsung anymore with the system reading as 1 GB of RAM instead of 1.5 GB. Tried every configuration and would only see the Kingston. It would only see the Samsung if I pulled out the Kingston regarless of the slots I use. So, I just bought the exact same make/model of Kingston and it recognized that fine and the system now has 2 GB of memory (max this board allows). And, I had already installed the latest BIOS for this board from Intel before doing all this so wasn't an old BIOS. I'm figuring the board didn't like something about the Samsung memory (speed, module configuration, etc.) that made it not play nice with the Kingston. If interested I bought the DM8400A/1G Kingston modules. And, this board appears not to support dual channel memory. Only has channel A, slots 0 and 1, and I read need two channels to support dual channel (seems obvious). Boards that supports dual channel memory normally have 4 memory slots, two for channel A and two for channel B, then put in matching modules in slot 0 for channel A and B and have dual channel memory access. And if want more ram, then matching modules in slot 1 for channel A and B.