Since iMac logic boards are not interchangeable we recommend that you email your iMac's serial number so that we can send you a link to the correct part -> email serial number
If you familiar with Macs you can select the part by its '661' part number. Or, by following the more information link corresponding to your iMac's EMC number and matching 'EEE' numbers.*
*The iMac's EMC number is printed on the bottom of its stand. Select 'What's This' on any product listing page for information about a part's 'EEE' number. If you know the EEE number use the Search Field at the top of the page.