New TwinMOS DDR memory cut in half?

[gopheryang]

Hi, yesterday I bought 256MBx2 and tried it. It's able to boot and everything, but Win2000, Sisoft Sandra, and my bios all say there's only 256mb of RAM. What happened to the other 256mb?

Computer:
mb- ASUS A7A266 (the one with 3 slots for SDR and 2 for DDR)
TwinMOS DDR 256MBx2 PC2100 CL2
cpu-Athlon 1.2G
HD-20G + 8G

I originally had two SDRam (128x2) and now I'm supposed to have DDR 512mb (256x2). I've browsed through my mb manual but I didn't change anything yet. Do I need to change anything when switching Ram types?
However, Sisoft Sandra detects a much higher mb/s after switching (9xxmb/s into 15xxmb/s).

Also, I heard from two local vendors and several online hardware reviewers that TwinMOS PC2100 has been verified to be able to run at PC2700 166FSB. Is that true:eek:?

[rextex]

What does Windows say in the general tab, or wherever if you're using XP?

--oh sorry-- i see you wrote the bios says it.Hmmm..
Check it and reseat it fully.
Enter the bios setup and just "save to cmos" and exit.That should trigger redetection.

[gopheryang]

I reset it by calling back bios defaults, then saving it, then rebooting. Didn't work:confused:.

Is it possible that a bios setting can affect whether the right mb shows up?

[gopheryang]

:) I've got it! 512MB in the bios. This was after my motherboard started to beap, forced the comp. to turn off, and reinserted a "suspicious" Ram stick. I guess I'll never know how to insert a ram properly (I did use all my force to push the ram down in the first try).

What are bios settings that affect Ram (I'm a newbie)? I might try to get to PC2700 even though my mb is for 266.

[Jimstep]

Did you leave the SDRAM memory in the motherboard?

[gopheryang]

No, I took my 256mb sdRam off.