Why can't my two RAM modules work together.I have a Nanya 256MB DDR-400Mhz-CL3 PC3200U-30330 that came with my Dell, and a 512MB PC3200 184Pin DIMM (part #C512M/IKVN) Centon module that was sent to me as a replacement for a 512MB that I purchased which went bad, but was fortunately covered by warranty. When I purchased the 512 from the store and installed it, it ran fine with my existing memory for about one year, at which point it failed and corrupted my system. My replacement memory, which Centon sent me, will not run if it is installed in conjunction to the 256MB. When I put both modules in and attempt to boot, all that happens is a couple of beeps and a flashing red light on the front of my Dell dimension 3000. If I install either chip individually my computer boots just fine. Do I have two incompatible pieces of memory? what exactly is going on? Anybody out there that may have an answer please let me know why I cant get these two pieces of memory to work together.

That to some point is not normal for DDR ram... But it is possible the combination of the 2 modules do not work together on the dell mother board.... best way to find out for sure is try each module in another computer and together also... The other option is, are they 2 modules both double or single sided ???? Some mother boards will not accept single and double sided ram modules in certain configurations... Its a proprietary computer so this sort of thing does not surprise me... IF IT AINT BROKE, DONT FIX IT A8N-SLI Deluxe AMD X64 3500+ Wnchst Corsair 2x512 DDR400 Dual Channel GV-NX6600128D PCIX Graphics Card Ggbyte GT Pro CPU Cooler Zalman VF700-CU VGA Cool

"Do I have two incompatible pieces of memory?" Seems like you do. "My replacement memory, which Centon sent me, will not run if it is installed in conjunction to the 256MB." You could negotiate with the vendor or with Centon for a stick like the one that did work with your existing memory.

Centon appears to have a nice configurator on their website. Did you check your part on this configurator?

I have found that Dell computers seem very picky on ram and i would not be at all suprised if they did work together on another computer but not on the dell

Some PC's/mobo's are more finicky than others. Ive heard some PC's look for memory "signatures" & if they are not what is expected, they don't recognize them. One potential problem I've had problems with is mixing memory types and/or speeds. In some systems, they will be incompatible & bizzare results will occur (other times they will work 100% perfectly). I agree with Badboy - work with the supplier to get the exact same memory type as what was working. Sometimes they "do you a favor" by providing you with updated components, that actually cause you as many problems than your original failure.

I did use the configurator on centons page, which says the chip is compatible. But I think Wallys right, I just need to try to get the exact same memory I sent in in the first place. Thanks for the help