experienced mac users I need help

[Dr_Hicks]

iMac 6.1 is a Core2Duo INTEL chip, the problem could be incorrectly seated ram module, after checking I think preforming a clean install of current OS would be best.

Here is the specs for 6.1 model.
http://www.everymac.com/systems/appl...nch-specs.html

I think you should remove the ram from the computer, make sure both chips are from the same manufacturer, the computer will handle OS X 10.7x so this means you can install Lion, right down to Tiger 10.4.

If you have a current mac with Lion installed, you can download this tool from Apple
http://support.apple.com/kb/DL1433?v...S&locale=en_US

Use it on your iMac 9.1, the tool will read the recovery partition, and then create a recovery on a USB drive; you can then use this USB drive to install Lion on the 6.1 iMac, do a completely fresh install, not an upgrade.

If you need help learning how to do a fresh install send me a PM I will help you with detailed instructions mate

edit--

Here is a link that will guide you though a clean install
http://osxdaily.com/2011/06/21/mac-o...all-explained/