RAM Limited to 256MB while 4GB installed

Question

I have a Dell PowerEdge 800 running, with 4 1GB RAM modules installed, totaling 4GB. But while doing POST, it displays a message saying "Amount of Memory Limited to 256MB" and checking System Monitor in Ubuntu (Ubuntu Jaunty Jackalope) the OS also reports 256MB in total.

What might be the problem?

Answer 1

This is on the Dell forums:

In the BIOS disable "OS Install Mode"

Answer 2

Put your install disk back in and try the memory test option

Answer 3

Pull the CMOS battery on the system board while the server power cord is unplugged. This worked for me in a PE1650 with the exact same issue, not 100% it will work for this system but worth a try.