RAM question

Hi, I have a Dimension 8300 which uses DDR400/PC3200 RAM in 4 sockets which I think are matched pairs.

I have original pair of 256Mb in the first slots. FINE.

I just bought a pair of 512Mb which I placed in the first slots and moved the two 256Mb to the second slots.

Computer started ok but when I run MemTest86 it crashes my machine and I have to turn it off and it stalls when I turn it on.

Now when I put the two 256Mb back into the first slots and the two 512Mb in the second slots everything is fine and MemTest86 runs for hours with no problems.

Should I be happy with this? And any ideas why this happens?

Thanks
Jim

You shouldn't mix and match different types of ram.

I don't know what combinations are okay if any, but even if it seems to work okay right now, who's to say it won't crash when you try to run some demanding application like a game?

If you need more than a gig of ram, you should probably just get another couple 512 sticks of the same brand.

It really depend son the memory and the motherboard. If you are mixing some single sided memory with double sided memory, then some motherboards will require that they be in specific slots.

If it is working, and it passes MemTest in that configuration, I vote it is good. Go ahead and use it.

Thanks guys, I played Call Of Duty and everything went fine .. it even told me I had changed my system. When I exited it the desktop popped back immediately .. it usually took about 20 secs.

I'm happy, so I'll keep it!
Thanks again
Jim