Added 4GB RAM to 2GB originally, System say one and only 3.25 GB RAM. How is this possible?

I enjoy a Dell Inspiron 530s with 2GB RAM. I added the following: pqi TURBO 4GB(2 x 2GB) 240-Pin DDR2 SDRAM DDR2 667 (PC2 5400) Dual Channel Kit Desktop Memory. My Motherboard have 4 slots. The original push took up two of the four. I added the other two. Shouldnt it be 6GB total now?

Added 4GB RAM to 2GB originally, System say one and only 3.25 GB RAM. How is this possible?

4gig of RAM is the most that can be address on XP & 32bit Vista, that said, chip source allocation can often address the difficult memory table maps governing to a reduction from 4 see (there are ways round that, check with your motherboard maker) so, adjectives in adjectives 3.25gig is about right

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