What kind of adapter do i need to connect an imac to a non mac monitor

Can you identify your PowerPC iMac?

Do an About This Mac from the Apple menu. Click More Info. System Profiler opens. Under Hardware Overview, what does it say for Machine Model.

According to website EveryMac.com, it is one of these iMac

http://everymac.com/systems/apple/imac/specs/imac_g5_1.9_17.html

http://everymac.com/systems/apple/imac/specs/imac_g5_2.1_20.html

which is the iMac G5 with iSight. These documents have more info

http://support.apple.com/kb/ht2833

http://support.apple.com/kb/HT2834

and say the part is called "Apple VGA Display Adapter (M8639G/A)." It's not available at the Apple Store, but when I did a Google search on "Apple VGA Display Adapter (M8639G/A)," there were links to vendors who seem to have it. This is one of the links.

http://www.amazon.com/Apple-Mini-VGA-display-PowerBook-603-0607/dp/B002PXV0S6

iMac PowerPCs only support mirroring to external display. There is a hack that changes the firmware and what it supports, but it could cause problems that are unforeseen. Matrox may make a multiple display adapter that is slow given the age of the iMac, but I would check with them if that gives you what you want.