According to the system specs it does not support memory above 2 Gigs

You are correct that the system does allocate system ram and video ram.  It also may be an issue with the 32 bit os and there is no way to change this. Going to a 64 bit OS might help but I still feel it is a system limitation.

According to the system specs it does not support memory above 2 Gigs   Memory Type 533- or 667-MHz DDR2 SDRAM Memory connectors two Memory modules supported 256-MB, 512-MB, or 1-GB non-ECC Minimum memory 256 MB Maximum memory 2 GB BIOS address F0000h     You are correct that the system does allocate system ram and video ram.  It also may be an issue with the 32 bit os and there is no way to change this. Going to a 64 bit OS might help but I still feel it is a system limitation.

Good reply, this is certainly interesting stuff, can you send me a link to that data sheet (sorry I'm not trying to be lazy poking around for it) 

I was able to run the 4 gig without the the PCI-e card (the system will load and display all of it in Windows), however, when the BIOS allocates the RAM for this new adapator this is probably where I'm running into this issue. 

I'm an electrical/computer engineering student - so I'm kind of overly interested in the issue-- wondering if I could crack open the BIOS or run a fix in some way to expand the addressing for my card so I can run all the RAM without replacing my whole board... 

Hmmm wondering what the results would be perhaps loading a BIOS for another similar board from Dell onto this one? Thoughts...? (probably crippling!)

I found that info HERE <ADMIN NOTE: Broken link has been removed from this post by Dell> in the system manual. That is strange that you had it running with the integrated video. That would make me really suspect that the allocation for the PCIe card causes an issue in the system allocating ram resources.

As a electical/computer engineer I would imagine you could figure out how to crack open the bios not sure how much good it would really do though.

Placing a non Dell bios on the boar would make a doorstop out of your system.

It could also be a voltage issue as the card may draw enough to load down the power supply and thus not be able to provide enough voltage to the memory stick when populating all four slots.

On a lot of the Dell systems the motherboards are very finicky about the voltage requirements for ram sticks when filling all the ram slots.

I found that info HERE <ADMIN NOTE: Broken link has been removed from this post by Dell>  in the system manual. That is strange that you had it running with the integrated video. That would make me really suspect that the allocation for the PCIe card causes an issue in the system allocating ram resources. As a electical/computer engineer I would imagine you could figure out how to crack open the bios not sure how much good it would really do though. Placing a non Dell bios on the boar would make a doorstop out of your system. It could also be a voltage issue as the card may draw enough to load down the power supply and thus not be able to provide enough voltage to the memory stick when populating all four slots. On a lot of the Dell systems the motherboards are very finicky about the voltage requirements for ram sticks when filling all the ram slots.

Davet I'm interested in your idea about the lack of power reaching all the slots. Ideally the same amount of voltage would be present across a 1 gig, 2 gig, or 4 gig single DIMM @ 667mhz

I guess than my question would be why would the computer be compatible with 2 1gig DIMMs (should be I guess, I haven't tried...) and the PCI-e slot enabled?

Otherwise does it make sense that a single 4 gig DIMM would require as much voltage as the single 2 gig DIMM I'm running now, and work as a potential solution to the issue of running the PCI-e slot and the memory DIMM at the same time...

I'm going to take this post over to overclock.net and post it in their voltage mod area and see if anyone thinks this is a good idea... Ill let you know 

I'd like to bump this post and see if any new information can be recovered about this issue:

reminding that even though the Optiplex 320 does not natively support 4GB of memory, it will run 4GB for me without the PCI-e slot filled! When the PCI-e slot is active I cannot run more than 1 memory DIMM.

Any ideas would be vary helpful.

Latest BIOS firmware installed.

Ok, I found some information that seems to argue that the Optiplex 320 natively supports 4GB of memory in 2x2GB DIMMs

This is a definite flaw in the Optiplex mainboard design and I would really like to understand it!

Tech specs sheet here:

http://www.dell.com/downloads/global/products/optix/en/opti_320techspecs.pdf

jebaucke

This probably does not help, but Crucial also states the Optiplex 320 supports 4gb of RAM [2 x 2gb modules] and Crucial certifies their memory to be compatible.

See HERE <ADMIN NOTE: Broken link has been removed from this post by Dell>

Bev.

jebaucke This probably does not help, but Crucial also states the Optiplex 320 supports 4gb of RAM [2 x 2gb modules] and Crucial certifies their memory to be compatible. See HERE <ADMIN NOTE: Broken link has been removed from this post by Dell> Bev.

It's possible using a different brand of RAM

I'm using Kingston RAM 2x2GB DIMMs, they work just fine without the PCI-e card but with it installed -- forget about it.

I'm about done with this and my other Dimension machine, I'm going to go with an HP (got a laptop on the way, and probably going to get another desktop from them as well)

Dear Dell,

I having same problem with this issue,

BIOS: Latest 1.1.12

OS: Windows 7 32 bit

I get only 2GB only when I plug-in another 2GB into 320 when have external PCI-E card plug-in.

Please try fix this problem.

Thank you very much.

Regard,

San

In general:

Onboard video: 4 GB of RAM is usually okay.

With a PCI-Express video card: 2 GB. 

4 GB RAM + PCI-Express Video Card = bad things happen.  I've confirmed this with a few cards:

1) ATI Radeon HD 2400 Pro: won't even POST.

2) GeForce GT 220: Will POST, but the slowdown issue described by jebauckle occurs.  Remove one 2 GB DIMM and replace it with a 1 GB DIMM and it will work with 3 GB of RAM.

3) GeForce 8400 GS: Will only see 2 GB of RAM max, even when 3 GB of RAM are being used.

All three tests were done with Windows 7 Professional x64, so it's not a 32-bit vs. 64-bit issue.  It's a motherboard issue with mapping address space above the 4 GB ceiling.  The OS can do it (if it's 64-bit Windows), but the motherboard cannot. 

Bottom line: With onboard video, listen to Crucial.  With a PCIe card, listen to Dell.

Killer B

So...here it is July 11, 2011 and Crucial still selling the 2 x 2 GB memory solution for the Dell Optiplex....and users still having trouble installing it.

I have installed each stick separately in each slot and they run fine, however when I put both in together I get 3 & 4 lit green on the front of the computer and the message for that light combo says "Memory modules are detected, but a memory failure has occurred."

<ADMIN NOTE: Broken link has been removed from this post by Dell>

The sticks are a matching set,  2 GB sticks @ 667

Have there been any new developments on this topic?

I have tried using just one of the 2 GB sticks with one of the original 512 sticks (don't know the speed).  The computer boots up fine and shows 2.5 GB of memory.  Will it hurt anything to run the computer this way?

If I decide to just use one 2 GB stick does it matter which slot I use?

Hopeful,

Susan

Processors and RAM

The Optiplex 320 series is designed around Intel Celeron, Pentium 4 and Pentium D processors. The motherboards have two DIMM slots for DDR-2 SDRAMs, providing up to 2GB of system RAM. Some users have reported using a pair of 2GB SDRAMS for a total of 4GB RAM, but were unable to do so if an aftermarket video card had been installed.

This answer was found at:  www.ehow.com/info_8046360_optiplex-320-specifications.html

Is it possible to attach a RAM of 800-MHz DDR2 in Optiplex 320 ?

No the system only support 667 mhz memory

No the system only support 667 mhz memory

Mine won't boot with either one or two PC6400 sticks and the speaker beeps an error code. I've ordered a DDR2-667 pair from eBay, but it won't ship until the new year. Word is that it won't support 4gb, so I'm not going to bother. Anyways, 2gb is enough for light duty use.

Currently, mine has 512mb. It will boot Windows 7 x64, but won't run anything, even Control Panel.