I recently updated by XP computer (MESH 32 bit Athlon 64 X2 4800 dual core 939 pin) to Windows 7 64 Bit successfully and decided to increase the memory from 2 GB to 4GB. However, when I added the extra two DDR cards, the compyter would not boot. However, when I installed just one of the new cards giving me 3GB in total, the system worked. The first boot up screen did show 4GB of memory, with the 4 cards in, but some how it does'n't like it. Any ideas?
Have you tried installing the "4th" module in the 3rd slot to see if it too would allow the system to boot with 3GB? Also, have you tried booting the system to safe mode with all 4GB installed? If not, this would be the first two things I would check. If the 4th module won't boot in the 3GB configuration, then it is possible you have a bad module. If it also boots and you are able to boot into safe mode it is possible that you have a weird driver issue going on. Let us know the results of these two tests and we will take it from there.