AppleInsider is noting that Apple will be refreshing the iMac lineup prior to the end of the year, it is expected that the iMacs will only receive minor specification changes.

AppleInsider expects the iMacs to receive similar CPU offerings to those seen in the MacBook Pro refresh earlier this week. This would mean CPU speeds remaining around the same. The iMac already has a 1066MHz front-side bus so no improvement is expected there.

Apple stated at its event last Tuesday that all Macs would be receiving DisplayPort so this is likely to replace the mini-DVI currently seen on the iMac.

Although not confirmed and AppleInsider is hesitant to add any certainty, it would be a fair expectation to see NVIDIA chipsets working their way into the iMac.

Currently the iMacs employ ATI Radeon HD 2400 or 2600 paired with an Intel chipset with a NVIDIA GeForce 8800 GT as a build-to-order option, it’s possible that Apple could simplify its offerings similar to those available in the current MacBook and MacBook Pro.

The iMac refresh is expected in mid-November but is likely to be a quiet affair.