A:AnswerHello,
You wouldn't be able to use what you already have in the system, and I'd recommend going with one of our apple certified kits for the iMac. Please reach out for more info if you can't locate the kit on our site: support.corsair.com
-Art
A:AnswerHello,
Please check your motherboard/system's manual for what you'd need. The CPU is DDR4 compatible, so this wouldn't work.
If you have anything else we can help with, please reach out: support.corsair.com
-Art
A:AnswerFrom looking at the intel website it appears that the board can support up to an 8GB 1333 MHZ DDR3 memory chip in each memory slot. This looks to be the biggest memory chip you could put on the board.
A:AnswerHi,
Unfortunately, no way to know without knowing which model you own. Please contact us with that information if you cannot locate compatibility information on your manual, we'd be able to help out: support.corsair.com