RAM issues??

[Ultra_Bloodshed]

Hey fellas...

I have an ASUS A8N-e MOBO... There are 4 ram slots in it... I have been using 1 gb of ram (512 * 512) installed in the 1st two slots, for some time now. Today, I tried installing additional 256 MB of RAM on the 3rd or 4th slot.

The problem is that when i use the 512*512 config, my bios shows that i am using 1 gb of ram.
But when i install the 256 MB RAM, the total memory shown in bios is 1280 MB but USABLE memory is only 512 MB??

Even dxdiag shows my total memory as 512 MB... What's happenin here?? How do I use the additional 256 MB ram with by 1 GB of ram??

[topgear]

When bios shows 1GB what does dxdiag show ? - you haven't mentioed it.

[RMN]

hmm....try placing the 512 sticks in dual channel.i.e in the alternating slots.