RAM Issue...

I'm betting that they are different speeds or maybe even different types one may be Low Density and the other High Density and the M'Board can not use the one that you are fitting last.

You can try removing the first one and fitting the second one and see if the system now works. If it does fit the Slowest RAM Stick closest to the CPU and try fitting the second stick in the correct Socket if you have more than 2 to allow the Dual Chanel RAM to work as it was designed to. Even then it may not as to get the most benefit of Dual Chanel RAM you should have 2 Identical Sticks.

Even if it works with the slowest RAM closest to the CPU you may experience random freezes or BSOD errors this is occurring because of Timing Issues between the different RAM and the only way to cure it it to either remove one and fit an identical Stick to the one left in the computer.

Of course if 1 Stick just doesn't work in this computer that means that the M'Board can not use that type of RAM. You really should look at the supported RAM list on the M'Board Makers Web Site to see what is required by this M'Board.

Col