Analyzing Retina iMac: How do you squeeze 5K out of a last-gen GPU?

21 Oct 2014 • extremetech.com

A late-2014 display hooked to an early 2012 GPU The GPU powering the 27-inch iMac with Retina 5K display is the R9 M290X, with the R9 M295X offered as an optional upgrade. The R9 M295X hasn’t technically been announced, but rumors from months back suggested this would be a Tonga-class GPU. Regardless, the R9 M290X is the minimum spec — and that chip is a rebranded HD 8970M, which was a rebranded HD 7970M, which is functionally equivalent to a desktop Radeon HD 7870.

Is all of this true? Does any of this matter?

One major point that Apple left out of the discussion is whether or not these monitors are 30Hz or 60Hz. Hopefully 60Hz — I expect 60Hz — but 30Hz wouldn’t surprise me.

I would like to know the answer to this.

Update: Gruber is saying 60Hz, but not officially confirmed.