The OP never said which iMac he had. Wouldn't the new iMac's with the 800Mhz system bus take advantage of the DDR2 800 ram?
Forgive me, but we have done this question in these forums many times already. There is a
Guide to intel Mac RAM for reference. The answer is - no it is locked at 667 due to the hardware memory controller on the motherboard.
Who offers the best no name brand RAM for Mac that's reliable and cheap?
That's a contradiction in terms. Generic or no-name brand RAM by definition can have different components and construction from month to month, or even week to week. Therefore, if Patriot or JetRAM or some in-house brand RAM worked for another user last month, there's no assurance you are getting the same RAM when you buy it this month. It could be a different chip entirely under the same label.
You can take a chance on generic DDR2-667 RAM and there is a 90 - 95% chance it will work in your intel Mac. You may save $10 or if you are unlucky or the seller is providing substandard RAM you may pay considerably more in trouble and return shipping costs.
As usual, however, I recommend choosing a reputable dealer who tests and guarantees compatibility with your Mac machine, and offers a no cost return (no shipping, no restocking) if it doesn't work.
