I had wanted to upgrade my RAM from 2x256 to that plus 2X512 for a gig and a half.  Conveniently, my brother needed and upgrade as well and was going to sell his 2x512 ram cheap.  The problem is, we both COMPLETELY forgot that there are compatibility issues with RAM.  So we took out the existing RAM from the 1 + 2 Dimm slots and replaced it with his 2 KINGMAX 512MB 184-Pin DDR SDRAM Unbuffered DDR 400 (PC 3200) System Memory - OEM.  I don't know how he managed to fit them in, since the are 184 pin and the DIMM fits 240 pin.  We turned on  the computer and it didn't turn on.  We were puzzled why since there was no error beeps.  Then I started to smell burning.  Then we turned it off. UH-OH!  We then inspected his RAM and there was no damage.  I put the original Dell ram back in 1+2 slot and turned the computer back on.  Well it turned on, but it was only reading 256 MB ram from DIMM 2 (Using My Computer, and BIOS).  I inpected DIMM 1 and found no damage in the pins.  So I tried mix matching the RAM and slots.

 

Here's a picture of the mother board http://support.dell.com/support/edocs/systems/dim4700/sm/techov.htm#wp1052788

 

I came to the conclusion that a single stick works in 2 + 4, but not in 1+3.  Those 2 pairs of DIMM slots are paired together on the motherboard.  I could have a single stick in 2 or 4 , and a stick in 1 or 3, and it would work.  It just wouldn't read the memory from the 1+3 pair.  I can understand why the 1 may not work, but the incompatible ram didn't even touch the DIMM 3.  So why are 1 and 3 not working?  Is there maybe damage that is not visible (from putting 2.5v ram in 1.8v slot)

 

I reset the BIOS but it didn't do any good.  I don't think that reseating the processor would do much good.  I really hope there isn't permanent damage to DIMM 1+3.  PLEASE help me.  I just bought a Geforce 7600GT and I can't play any high end games without at least 1 gig of RAM.

 

Thanks,

 

Mark Glaser