I am trying to install new RAM in my friends iMac, something I have done several times before. We unplugged the computer before performing the upgrade, used anti static wrist bands, and yes the memory is compatible and inserted correctly.

The stock RAM was Hynix 1gb pc2-5300s-555-12 and the memory we are replacing it with is 2x2gb Centon CMP800SO2048.01. Now I know this model number suggests that the ram is 800MHz and the iMac is only 667MHz but it clearly states on the box that this RAM is PC2-5300 667MHz compatible.

The problem is, that when I install the new RAM I get little response from the computer. I hear the hard drive and disk drive start to initialize, but then they just stop and the screen remains black. I have tried every variation of the new RAM and the old RAM in both slots and even tried the same RAM from my old iMac and I just can't get it to boot. Has anyone ever had a problem like this?

Thank you in advance for any and all input on thus issue!