I have a motherboard capable of 4GB of RAM using 4 slots. So, there are two pair, each slot having 1GB sticks to produce the full 4GB of memory.

I originally had 2GB and then added 2 X 512MB in the unused pair slots to reach 3GB. This worked fine. Now I have removed the 512MB sticks and replaced them using exactly the same 1GB sticks (2 x 1GB). This should bring the total memory to 4096MB - but, at boot time and in Windows it only shows 3378MB. Running diagnostic programs to examine what is found in the slots - they show 4 1GB sticks.

When I install only one pair in either 1-3 or 2-4 slots it shows 2048MB. Switching to the other pair of sticks I get the same result.

What is going on here? I have not experienced this before.

Thanks, Bob

Hello Bob Welcome to PCHF

This is a very common question these days. 32-bit Windows 98, XP, Vista will only address up to 3.12 gigabytes of memory. In actuality, a 32-bit memory bus can address up to 4 gigs. But Windows reserves the last ~800 megabytes for some other Windows related stuff (a little bit beyond my understanding).

So there is not really a reason to upgrade past 3 gigs of memory if you have a 32 bit version of Windows. You may want to return the new memory and go back to your old setup. Realistically, for most purposes, you don't even need 3 gigs of memory, let alone 4.

Hope that helps!

That's true, 32 bit windows will only display about 3.25gb memory, to see all 4gb you'd need to get a 64 bit version