Replace it....
A ) When your cpu doesn't run the games, apps, etc.. you want, at the speeds you want.
B ) When your cpu / rig is starting to have random hardware related problems.
C ) When you get the "itch" to upgrade.
I'm still running my 2500K @ 4.3Ghz, even though I have a brand new 3570K / board combo sitting here. It might sit here for a while because the 4790K for $249 @ MicroCenter pretty tempting.
A ) When your cpu doesn't run the games, apps, etc.. you want, at the speeds you want.
B ) When your cpu / rig is starting to have random hardware related problems.
C ) When you get the "itch" to upgrade.
I'm still running my 2500K @ 4.3Ghz, even though I have a brand new 3570K / board combo sitting here. It might sit here for a while because the 4790K for $249 @ MicroCenter pretty tempting.