Mac's don't have the same issue as that other OS ;-}
Here's a good reference: [http://support.apple.com/kb/HT2422|Mac OS X: Mac OS Extended format (HFS Plus) volume and file limits].
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As far as the socket there are a few different models in this series. I would strongly recommend you review the [http://www.everymac.com/systems/apple/imac/index-imac.html|EveryMac] web site to double check which system you have using the last three digits of the systems serial number. Once you locate the system locate the CPU and then refer to the [http://ark.intel.com|Intel ARC] web site to then cross reference what is possible with that series system. Be careful here! You need to not only worry about the socket but also the Max TMP as well as the North & South bridge chips needed for the replacement CPU.
Mac's don't have the same issue as that other OS ;-}
Here's a good reference: [http://support.apple.com/kb/HT2422|Mac OS X: Mac OS Extended format (HFS Plus) volume and file limits].