What happens when more RAM is installed than the motherboard supports?

Question

I have a free RAM slot and some spare memory that will fit my computer. However the problem is my motherboard only supports 2GB and I have 2GB installed. What would happen if I plugged the spare memory in the RAM slot?

The following things spring to mind:

• Nothing will happen
• It will work, computer becomes faster
• Computer becomes slower
• Explosion
• Undetermined (Any of the above)

Does anyone have any experience of this?

Update: Egged on by you zealous lot, I went ahead and stuck the extra memory in. It booted up! Unfortunately, the hunch of some has been proved correct. The memory is reported at the capped limit, rather then the actual available. A shame then! But thank you all for your suggestions, speculations and stories.

For your reference, I am using a Dell Insprion 6000 with 2gb installed, latest drivers. I attempted to add 512mb, with no success.

Answer 1

Simple answer: It either will only see the max supported memory or it will not work at all.

My gut feeling says two things:

If it does work, you just will not see the extra memory, only the max the motherboard/chipset supports. If it doesn't work, it usually will just beep at you with a memory error and you will get no video responce. All depends on the motherboard depending on how it handles memory errors.

Someone on Yahoo answers says an interesting bit about getting a blue screen due to this:

In my experience, putting in more than the max amount of RAM as specified by the manufacturer will cause the computer to not boot up.

others claim:

Some won't POST, some will and simply BSOD (kernel panic, etc) with PFN_LIST_CORRUPT.

That said, the "max" memory isn't always the actual max. Case in point, Intel states the GL960 chipset (such as in my laptop) supports a max of 2GB of memory. 4GB is a no-go, but 3GB works.

Answer 2

your first stop is the mainboard manufacturer's website. update the BIOS to the latest version. then fit the additional memory and turn on the computer, if the memory is detected, run MemTest86+. no, it won't explode! :)

Answer 3

Depends on the board and BIOS. I have a Sony VAIO VGN-Fe770G that uses the GM945 chipset -- Intel, Sony, AND Crucial say that the maximum amount of RAM is 2GBs of DDR2 (1 GB per SODIMM slot), but I'm running Windows 7 x86 with 3GBs and both the BIOS and Windows report (and presumably map) all 3072MBs. I'm going to try with a second 2GB DDR2 SODIMM and see if the BIOS and a 64-bit LiveCD OS sees 4096MBs.

Answer 4

This really depends on your MotherBoard. I have seen some cases where the system functions as normal but will only recognize the 2gb, and I have seen some that will not start up and throw an error.

I have yet to see any of the hardware fail because of an "over-installation".

Answer 5

Been there, done this. The BIOS complained about the RAM and refused to start up. I had to downgrade again. But this was an old Pentium 133 from Dell and about 4 PC's in the past.

In general, it will depend on the BIOS and hardware. It won't be able to handle the big modules but if there are still smaller modules available, the system might decide to just start up with the memory of just the smaller modules. But in general, the BIOS won't be able to use it thus your system would have no free RAM to use.

Answer 6

I've done it on an older computer, and the computer booted just fine - however the BIOS / start up scrolling list only reported what the maximum for the motherboard was, so it was presumably ignored.

Now wether that's unsafe or not, i don't know, but i'd simply leave only up to the max in to be safe.

Answer 7

I tried to installed 4GB on a HP 6720s that only supports up to 3GB, and what happened was that the BIOS saw the memory, but with any type of memory check an error was reported.

And trying to install an OS (not even x64) was impossible, I got a memory related BSOD every time.

I found out later on that some 6720s moderboards supported 4GB, but not mine... :(

Answer 8

Assuming that you install the correct type that this motherboard accepts, anything above 2GB won't be addressed and will be ignored.

Answer 9

I have an HP Compaq dc7600 desktop with an OEM-reported 3GB max. I have 6GB installed. The BIOS and Windows 7 Ultimate both recognize the extra RAM, but sysinfo shows:

Installed memory (RAM): 6.00 GB (3.25 GB usable).

Even so, when I upgraded from 4GB (which was already over the max) to 6 GB, the processor usage decreased across the board. Not being an engineer, I can't explain it, but it's not my imagination.

One possibility I thought of is that although the memory may not be directly accessible, Windows does "see" it and thus is more brave in its allocation of RAM resources versus virtual memory.

Answer 10

I haven't tried this but I think the motherboard will just completely ignore it.

Answer 11

I got a 2.5GB with system limit of 2 GB and it works.

Answer 12

I have an Hp Pavilion 7935 that supports a max of 512mb of ram. I have installed 1 gig in it. currently using it that way. It boots and runs fine (Bios shows 992 Mb)

Answer 13

the mother board just ignore it. My computer is a HP pavillion a1600n max of 4 GB and I have two slot with 2 GB and two other with 500 MB and the computer read only 4 GB

Answer 14

Im using an emachines d620 notebook. Recently it became very slow and the system health report suggested i decrease the load or upgrade the memory. I did later by taking my pc to an expert who installed a 2gb memory module. The initial RAM was 1GB. The guide set the limit of RAM that can be added at 1GB. My RAM is now 3GB and the rest of the memory that is not in use is shown as being available. Believe me my pc is working perfectly and its faster than ever.