Apple on Tuesday updated its 21.5-inch iMac with Retina display and 27-inch iMac with Retina 5K display with new processors and graphics chips that include a lot more power. The company's entry-level iMac without a Retina display was not updated.

The new 21-inch iMac with 4K display will start at $1,299, but you'll need to pay more for the bump up to the new six-core processor Apple will offer. The 27-inch iMac with Retina 5K will start at $1,799. Both go on sale Tuesday and ship next week.

The iMac announcement comes just one day after Apple announced a new iPad Air and iPad Mini, so Apple is appears to be getting all of its new hardware announcements out of the way this week ahead of its March 25 event, where it's expected to reveal new services including a streaming TV platform and Apple News with magazine subscriptions.

Apple didn't update the iMac at all in 2018. It's been 14 months since Apple refreshed the family , so it's due time for a bump in processor speed and graphics. They look the exact same as the earlier models, though. So there's no support for anything fancy like FaceID or even TouchID, the latter of which has made its way into Apple's latest MacBooks. Also, while the screens look great, they still have some pretty large bezels around the side, which I think is starting to look a bit dated.

Instead, the changes are all under the hood.