New Memory

[shadowgate]

So bought 2 gig of new PNY DDR400 memory. Problem is that I don't seem to be able to leave half my old memory in with it to hit 2.5 gig. Anyone know why that would be? Boots up fine with the old memory in four slots to make 1 gig but when I added the two 1 gig simms in it wouldn't fully boot up Windows. Tooks the .5 gig out and it boots up fine...

[Gaelrond]

My guess is either that your motherboard is capped at 2GB of memory, or the old DIMM is a different speed than the new stuff.

[leng]

Is it the same speed? Do you need to be careful which slots the cards are in?
Might help to know which MB we are looking at.

[Raveneye]

Are the 4 memory slots color coded (usually green and purple)? Old mobos used to have the layout where if you wanted to use two memory sticks you put them in the first two slots. Newer mobos alternate slots, so you might need to put the new mem in the green slots and the old mem in the purple for example.

If the memory is different speeds even that may not work and you may not be able to use the old memory in conjuction with with new.

[Prescient]

DDR memory allows different speed memory to be put on the same motherboard. It just clocks down to the lowest speed. DDR is much more tolerant of speed mixing that old SDRAM was.

I'm guessing either a cap on the max memory or the memory sticks just don't like each other. I've seen brands that just will not work together. Also go into the BIOS and see how much memory the system is actually seeing when you have all the memory in.

Can also try running Memtest86 (http://www.memtest86.com/). If the sticks pass when you have them in one at a time but fail when all are in together, then they just don't like each other.