Trying to upgrade RAM

I am trying to upgrade my memory in my Acer T180 with Acer EM61SM MB.

I bought an OCZ kit (2 X 1GB) Found out my MB has a fixed voltage of 1.8 so couldn't use.

Now have Mushkin kit (2 X 1GB) Pc 6400 800mhz. I made sure it is 1.8v.

If I put in one stick at a time it boots fine. If I put in both sticks, the computer beeps and doesn't boot. If I remove the MB battery to reset CMOS is will boot fine, and works fine until I turn it off, and again it beeps, and I have to reset CMOS.

Any ideas???

 

What is the maximum RAM your PC will handle? Does it call for PC6400? Might be a setting in the Bios setup screens to change the RAM frequency.